View source for Brain tumor

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{{short description|Neoplasm in the brain}}
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{{Use dmy dates|date=December 2022}}
{{Infobox medical condition (new)
| name          = Brain tumor
| synonyms      = Intracranial neoplasm, brain tumour, brain cancer
| image         = Hirnmetastase_MRT-T1_KM.jpg
| caption       = [[Brain metastasis]] in the right [[cerebral hemisphere]] from [[lung cancer]], shown on [[magnetic resonance imaging]]
| field         = [[Neurosurgery]], [[neuro-oncology]]
| symptoms      = Vary depending on the part of the brain involved, [[headache]]s, [[seizure]]s, problem with [[visual perception|vision]], [[vomiting]], [[cognition|mental]] changes<ref name=PDQ2014MD/><ref name=PDQ2014Pt/>
| complications = 
| onset         = 
| duration      = 
| types         = Malignant, benign<ref name=PDQ2014Pt/>
| causes        = Usually unknown<ref name=PDQ2014Pt/>
| risks         = [[Neurofibromatosis]], exposure to [[vinyl chloride]], [[Epstein–Barr virus]], [[ionizing radiation]]<ref name=PDQ2014MD/><ref name=PDQ2014Pt/><ref name=WCR2014CNS/>
| diagnosis     = [[Computed tomography]], [[magnetic resonance imaging]], [[tissue biopsy]]<ref name=PDQ2014MD/><ref name=PDQ2014Pt/>
| differential  = 
| prevention    = 
| treatment     = [[Surgery]], [[radiation therapy]], [[chemotherapy]]<ref name=PDQ2014MD/>
| medication    = [[Anticonvulsant]]s, [[dexamethasone]], [[furosemide]]<ref name=PDQ2014MD/>
| prognosis     = Average [[five year survival rates|five-year survival rate]] 33% (US)<ref name=SEER2019/>
| frequency     = 1.2 million nervous system cancers (2015)<!-- prevalence --><ref name=GBD2015Pre>{{cite journal | title = Global, regional, and national incidence, prevalence, and years lived with disability for 310 diseases and injuries, 1990-2015: a systematic analysis for the Global Burden of Disease Study 2015 | journal = Lancet | volume = 388 | issue = 10053 | pages = 1545–1602 | date = October 2016 | pmid = 27733282 | pmc = 5055577 | doi = 10.1016/S0140-6736(16)31678-6 | vauthors = Vos T, Allen C, Arora M, Barber RM, Bhutta ZA, Brown A, etal | collaboration =GBD 2015 Disease and Injury Incidence and Prevalence Collaborators }}</ref>
| deaths        = 228,800 (worldwide, 2015)<ref name=GBD2015De>{{cite journal | vauthors = Wang H, Naghavi M, Allen C, Barber RM, Bhutta ZA, Carter A, etal | collaboration = GBD 2015 Mortality and Causes of Death Collaborators | title = Global, regional, and national life expectancy, all-cause mortality, and cause-specific mortality for 249 causes of death, 1980-2015: a systematic analysis for the Global Burden of Disease Study 2015 | journal = Lancet | volume = 388 | issue = 10053 | pages = 1459–1544 | date = October 2016 | pmid = 27733281 | pmc = 5388903 | doi = 10.1016/S0140-6736(16)31012-1 }}</ref>
}}
A '''brain tumor''' (sometimes referred to as '''brain cancer''') occurs when a group of cells within the [[Human brain|brain]] turn cancerous and grow out of control, creating a mass. There are two main types of [[tumor]]s: malignant (cancerous) tumors and [[benign tumor|benign]] (non-cancerous) tumors.<ref name="PDQ2014Pt">{{cite web |date=14 April 2014 |title=General Information About Adult Brain Tumors |url=http://www.cancer.gov/cancertopics/pdq/treatment/adultbrain/Patient/page1/AllPages |url-status=live |archive-url=https://web.archive.org/web/20140705225928/http://www.cancer.gov/cancertopics/pdq/treatment/adultbrain/Patient/page1/AllPages |archive-date=5 July 2014 |access-date=8 June 2014 |website=NCI}}</ref> These can be further classified as [[primary tumor]]s, which start within the brain, and [[metastasis|secondary]] tumors, which most commonly have spread from tumors located outside the brain, known as [[brain metastasis]] tumors.<ref name="PDQ2014MD" /> All types of brain tumors may produce symptoms that vary depending on the size of the tumor and the part of the brain that is involved.<ref name="PDQ2014Pt" /> Where symptoms exist, they may include [[headaches]], [[seizure]]s, problems with [[visual perception|vision]], [[vomiting]] and [[cognition|mental]] changes.<ref name="PDQ2014MD">{{cite web|title=Adult Brain Tumors Treatment|url=http://www.cancer.gov/cancertopics/pdq/treatment/adultbrain/HealthProfessional/page1/AllPages|website=NCI|access-date=8 June 2014|date=28 February 2014|url-status=live|archive-url=https://web.archive.org/web/20140705230128/http://www.cancer.gov/cancertopics/pdq/treatment/adultbrain/HealthProfessional/page1/AllPages|archive-date=5 July 2014}}</ref><ref name="PDQ2014Pt" /><ref>{{cite book | vauthors = Longo DL |title=Harrison's principles of internal medicine |year=2012 |publisher=McGraw-Hill |isbn=978-0-07-174887-2 |page=3258 |edition= 18th|chapter=369 Seizures and Epilepsy}}</ref> Other symptoms may include difficulty walking, speaking, with sensations, or [[unconsciousness]].<ref name=PDQ2014MD/><ref name=WCR2014CNS/>

The cause of most brain tumors is unknown, though up to 4% of brain cancers may be caused by CT scan radiation.<ref name=PDQ2014Pt/><ref name="nrsCT1">{{cite journal |last1=Smoll |first1=Nicolas R |last2=Brady |first2=Zoe |last3=Scurrah |first3=Katrina J |last4=Lee |first4=Choonsik |last5=Berrington de González |first5=Amy |last6=Mathews |first6=John D |title=Computed tomography scan radiation and brain cancer incidence |journal=Neuro-Oncology |date=6 July 2023 |volume=25 |issue=7 |pages=1368–1376 |doi=10.1093/neuonc/noad012 |pmid=36638155 |pmc=10326490 }}</ref> Uncommon [[Risk factor (epidemiology)|risk factor]]s include exposure to [[vinyl chloride]], [[Epstein–Barr virus]], [[ionizing radiation]], and inherited syndromes such as [[neurofibromatosis]], [[tuberous sclerosis]], and [[von Hippel-Lindau Disease]].<ref name=PDQ2014MD/><ref name=PDQ2014Pt/><ref name=WCR2014CNS/> Studies on [[Mobile phone radiation and health|mobile phone exposure]] have not shown a clear risk.<ref name=WCR2014CNS/> The most common types of primary tumors in adults are [[meningioma]]s (usually benign) and [[astrocytoma]]s such as [[glioblastoma]]s.<ref name=PDQ2014MD/> In children, the most common type is a malignant [[medulloblastoma]].<ref name=WCR2014CNS/> Diagnosis is usually by [[medical examination]] along with [[computed tomography]] (CT) or [[magnetic resonance imaging]] (MRI).<ref name=PDQ2014Pt/> The result is then often confirmed by a [[biopsy]]. Based on the findings, the tumors are divided into [[Grading of the tumors of the central nervous system|different grades of severity]].<ref name=PDQ2014MD/>

Treatment may include some combination of [[surgery]], [[radiation therapy]] and [[chemotherapy]].<ref name=PDQ2014MD/> If seizures occur, [[anticonvulsant]] medication may be needed.<ref name=PDQ2014MD/> [[Dexamethasone]] and [[furosemide]] are medications that may be used to decrease swelling around the tumor.<ref name=PDQ2014MD/> Some tumors grow gradually, requiring only monitoring and possibly needing no further intervention.<ref name=PDQ2014MD/> [[Cancer immunotherapy|Treatments that use a person's immune system]] are being studied.<ref name=PDQ2014Pt/> Outcomes for malignant tumors vary considerably depending on the type of tumor and how far it has spread at diagnosis.<ref name=WCR2014CNS/> Although benign tumors only grow in one area, they may still be life-threatening depending on their size and location.<ref>{{cite web |title=Benign brain tumour (non-cancerous) |url=https://www.nhs.uk/conditions/benign-brain-tumour/ |website=nhs.uk |access-date=29 July 2019 |language=en |date=20 October 2017}}</ref> Malignant glioblastomas usually have very poor outcomes, while benign meningiomas usually have good outcomes.<ref name=WCR2014CNS/> The average [[five-year survival rate]] for all (malignant) brain cancers in the United States is 33%.<ref name=SEER2019>{{cite web |title=Cancer of the Brain and Other Nervous System – Cancer Stat Facts |url=https://seer.cancer.gov/statfacts/html/brain.html |website=SEER |access-date=22 July 2019 }}</ref>

Secondary, or [[metastatic]], brain tumors are about four times as common as primary brain tumors,<ref name=PDQ2014Pt/><ref name=Mer2012>{{cite journal | vauthors = Merrell RT | title = Brain tumors | journal = Disease-a-Month | volume = 58 | issue = 12 | pages = 678–89 | date = December 2012 | pmid = 23149521 | doi = 10.1016/j.disamonth.2012.08.009 }}</ref> with about half of metastases coming from [[lung cancer]].<ref name=PDQ2014Pt/> Primary brain tumors occur in around 250,000 people a year globally, and make up less than 2% of cancers.<ref name=WCR2014CNS>{{cite book|title=World Cancer Report 2014.|chapter-url=http://publications.iarc.fr/Non-Series-Publications/World-Cancer-Reports/World-Cancer-Report-2014|date=2014|publisher=World Health Organization|isbn=978-92-832-0429-9|chapter=Chapter 5.16|url-status=live|archive-url=https://web.archive.org/web/20160919073553/http://publications.iarc.fr/Non-Series-Publications/World-Cancer-Reports/World-Cancer-Report-2014|archive-date=19 September 2016}}</ref> In children younger than 15, brain tumors are second only to [[acute lymphoblastic leukemia]] as the most common form of cancer.<ref name=WCR2014Peads>{{cite book|title=World Cancer Report 2014.|date=2014|publisher=World Health Organization|isbn=978-92-832-0429-9|pages=Chapter 1.3}}</ref> In New South Wales, Australia in 2005, the average lifetime economic cost of a case of brain cancer was AU$1.9 million, the greatest of any type of cancer.<ref>{{cite web|title=Brain Tumour Facts 2011|url=http://www.btaa.org.au/BrainTumourFactSheet2011.pdf|website=Brain Tumour Alliance Australia|access-date=9 June 2014|archive-url=https://web.archive.org/web/20140125234503/http://www.btaa.org.au/BrainTumourFactSheet2011.pdf|archive-date=25 January 2014}}</ref>
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==Signs and symptoms==
The signs and symptoms of brain tumors are broad. People may experience symptoms regardless of whether the tumor is benign (not cancerous) or [[Malignancy|cancerous]].<ref>{{Cite web|url=http://www.merckmanuals.com/home/brain,-spinal-cord,-and-nerve-disorders/tumors-of-the-nervous-system/brain-tumors|title=Brain Tumors|access-date=2 August 2016|url-status=live|archive-url=https://web.archive.org/web/20160812032003/http://www.merckmanuals.com/home/brain,-spinal-cord,-and-nerve-disorders/tumors-of-the-nervous-system/brain-tumors|archive-date=12 August 2016}}</ref> Primary and secondary brain tumors present with similar symptoms, depending on the location, size, and rate of growth of the tumor.<ref name="abta.org">{{Cite web|url=http://www.abta.org/brain-tumor-information/symptoms/mood-swings.html|title=Mood Swings and Cognitive Changes {{!}} American Brain Tumor Association|website=abta.org|access-date=3 August 2016|archive-url=https://web.archive.org/web/20160802203516/http://www.abta.org/brain-tumor-information/symptoms/mood-swings.html|archive-date=2 August 2016}}</ref> For example, larger tumors in the frontal lobe can cause changes in the ability to think. However, a smaller tumor in an area such as [[Wernicke's area]] (small area responsible for language comprehension) can result in a greater loss of function.<ref>{{Cite web|url=http://www.brainsciencefoundation.org/bUnderstandbPrimaryBrainTumors/AdditionalResources/CopingWithPersonalityBehavioralChanges/tabid/283/Default.aspx|title=Coping With Personality & Behavioral Changes|website=brainsciencefoundation.org|access-date=3 August 2016|url-status=usurped|archive-url=https://web.archive.org/web/20160730063637/http://www.brainsciencefoundation.org/bUnderstandbPrimaryBrainTumors/AdditionalResources/CopingWithPersonalityBehavioralChanges/tabid/283/Default.aspx|archive-date=30 July 2016}}</ref>

===Headaches {{anchor|Headache}}===
Headaches as a result of raised [[intracranial pressure]] can be an early symptom of brain cancer.<ref name=":0">{{cite journal | vauthors = Kahn K, Finkel A | title = It IS a tumor -- current review of headache and brain tumor | journal = Current Pain and Headache Reports | volume = 18 | issue = 6 | article-number = 421 | date = June 2014 | pmid = 24760490 | doi = 10.1007/s11916-014-0421-8 | s2cid = 5820118 }}</ref> However, isolated headache without other symptoms is rare, and other symptoms including visual abnormalities may occur before headaches become common.<ref name=":0" /> Certain warning signs for headache exist which make the headache more likely to be associated with brain cancer.<ref name=":0" /> These are defined as "abnormal neurological examination, headache worsened by [[Valsalva maneuver]], headache causing awakening from sleep, new headache in the older population, progressively worsening headache, atypical headache features, or patients who do not fulfill the strict definition of migraine".<ref name=":0" /> Other associated signs are headaches that are worse in the morning or that subside after vomiting.<ref>{{Cite web|date=2020-11-19|title=Nosebleeds & Headaches: Do You Have Brain Cancer?|url=https://ana-neurosurgery.com/symptoms-brain-tumor/|access-date=2020-11-26|website=Advanced Neurosurgery Associates|language=en-US}}</ref>

===Location-specific symptoms===
[[File:Brain headBorder.jpg|thumb|upright=1.3|The main areas of the brain and [[limbic system]]]]
The brain is divided into lobes and each lobe or area has its own function.<ref name=":02">{{cite journal |last1=Gregg |first1=N. |last2=Arber |first2=A. |last3=Ashkan |first3=K. |last4=Brazil |first4=L. |last5=Bhangoo |first5=R. |last6=Beaney |first6=R. |last7=Gullan |first7=R. |last8=Hurwitz |first8=V. |last9=Costello |first9=A. |last10=Yágüez |first10=L |title=Neurobehavioural changes in patients following brain tumour: patients and relatives perspective |journal=Supportive Care in Cancer |date=November 2014 |volume=22 |issue=11 |pages=2965–2972 |doi=10.1007/s00520-014-2291-3 |pmid=24865878 }}</ref><ref name=":1">{{Cite web|url=http://www.brainsciencefoundation.org/bUnderstandbPrimaryBrainTumors/AdditionalResources/CopingWithPersonalityBehavioralChanges/tabid/283/Default.aspx|title=Coping With Personality & Behavioral Changes|website=brainsciencefoundation.org|access-date=27 July 2016|url-status=usurped|archive-url=https://web.archive.org/web/20160730063637/http://www.brainsciencefoundation.org/bUnderstandbPrimaryBrainTumors/AdditionalResources/CopingWithPersonalityBehavioralChanges/tabid/283/Default.aspx|archive-date=30 July 2016}}</ref> A tumour in any of these lobes may affect the area's performance. The symptoms experienced are often linked to the location of the tumour, but each person may experience something different.<ref name=":22">{{Cite web|url=http://www.abta.org/brain-tumor-information/symptoms/mood-swings.html?referrer=https://www.google.com/ |title=Mood Swings and Cognitive Changes {{!}} American Brain Tumor Association |website=abta.org |access-date=27 July 2016 |archive-url=https://web.archive.org/web/20160815110242/http://www.abta.org/brain-tumor-information/symptoms/mood-swings.html?referrer=https%3A%2F%2Fwww.google.com%2F |archive-date=15 August 2016  }}</ref>
* [[Frontal lobe]]: Tumours may contribute to poor reasoning, inappropriate social behavior, personality changes, poor planning, lower inhibition, and decreased production of speech ([[Broca's area]]).<ref name=":22" />
* [[Temporal lobe]]: Tumours in this lobe may contribute to poor memory, loss of hearing, and difficulty in language comprehension ([[Wernicke's area]] is located in this lobe).<ref name=":1" />
* [[Parietal lobe]]: Tumours here may result in poor interpretation of languages, difficulty with speaking, writing, drawing, naming, and recognizing, and poor spatial and visual perception.<ref>{{Cite web|url=https://mayfieldclinic.com/pe-braintumor.htm|title=Brain Tumors: an introduction| vauthors = Warnick R |date=August 2018|website=Mayfield Brain and Spine Clinic}}</ref>
* [[Occipital lobe]]: Damage to this lobe may result in poor vision or loss of vision.<ref>{{Cite web|url=https://www.thebraintumourcharity.org/understanding-brain-tumours/symptoms-and-information/changes-vision/|title=Changes in Vision – Brain Tumour Symptoms|website=thebraintumourcharity.org|access-date=9 February 2018|archive-url=https://web.archive.org/web/20180210002520/https://www.thebraintumourcharity.org/understanding-brain-tumours/symptoms-and-information/changes-vision/|archive-date=10 February 2018}}</ref>
* [[Cerebellum]]: Tumours in this area may cause poor balance, muscle movement, and posture.<ref name=":3">{{Cite web|url=https://www.chw.org/medical-care/macc-fund-center/conditions/oncology/brain-tumors|title=Brain Tumors|date=6 March 2019|website=Children's Hospital of Wisconsin}}</ref>
* [[Brainstem|Brain stem]]: Tumours on the brainstem can cause seizures, endocrine problems, respiratory changes, visual changes, headaches and partial paralysis.<ref name=":3" />
* [[Leptomeninges]]: Tumours that spread to the leptomeninges, the lining of the brain, may cause [[cranial nerve palsies]] such as [[facial paralysis]], abnormalities of eye movement, abnormalities of facial sensation or [[dysphagia|swallowing difficulty]], depending on which cranial nerves are involved.<ref name="Schaff 2023">{{cite journal |last1=Schaff |first1=Lauren R. |last2=Mellinghoff |first2=Ingo K. |title=Glioblastoma and Other Primary Brain Malignancies in Adults: A Review |journal=JAMA |date=21 February 2023 |volume=329 |issue=7 |pages=574–587 |doi=10.1001/jama.2023.0023|pmid=36809318 |pmc=11445779 }}</ref>

===Behaviour changes===
A person's personality may be altered due to the tumor damaging lobes of the brain. Since the frontal, temporal, and parietal lobes<ref name="abta.org"/> control inhibition, emotions, mood, judgement, reasoning, and behavior, a tumor in those regions can cause inappropriate social behavior,<ref name=":52">{{Cite web|url=http://milesforhope.org/index.php/facts/brain-tumor-symptoms|title=Brain Tumor Symptoms {{!}} Miles for Hope {{!}} Brain Tumor Foundation| vauthors = Jones C |website=milesforhope.org|access-date=3 August 2016|archive-url=https://web.archive.org/web/20160814084958/http://milesforhope.org/index.php/facts/brain-tumor-symptoms|archive-date=14 August 2016}}</ref> temper tantrums,<ref name=":52"/> laughing at things which merit no laughter,<ref name=":52"/> and even psychological symptoms such as depression and anxiety.<ref name=":22"/> More research is needed into the effectiveness and safety of medication for depression in people with brain tumors.<ref>{{cite journal | vauthors = Beevers Z, Hussain S, Boele FW, Rooney AG | title = Pharmacological treatment of depression in people with a primary brain tumour | journal = The Cochrane Database of Systematic Reviews | volume = 2020 | article-number = CD006932 | date = July 2020 | issue = 7 | pmid = 32678464 | pmc = 7388852 | doi = 10.1002/14651858.CD006932.pub4 }}</ref>

Personality changes can have damaging effects such as unemployment, unstable relationships, and a lack of control.<ref name=":02" />

==Cause==
A known cause of brain cancers is [[ionizing radiation]].<ref name=nrsCT1/><ref name="nrsIR1">{{cite journal | last1=Smoll | first1=Nicolas R. | last2=Brady | first2=Zoe | last3=Scurrah | first3=Katrina | last4=Mathews | first4=John D. | title=Exposure to ionizing radiation and brain cancer incidence: The Life Span Study cohort | journal=Cancer Epidemiology | date=June 2016 | volume=42 | pages=60–65 | doi=10.1016/j.canep.2016.03.006 | pmid=27038588 }}</ref> Approximately 4% of brain cancers in the general population are caused by [[CT-scan]] radiation.<ref name="nrsCT1" /> For brain cancers that follow a CT scan at lags of 2 years or more, it has been estimated that 40% are attributable to CT-scan radiation.<ref name="nrsCT1" /> The risk of brain cancer is dose dependent, with the relative risk increasing by 0.8 for each 100 [[Gray (unit)|gray]] of ionizing radiation received. At this dose, approximately 6391 people would have to be exposed to cause 1 case of brain cancer.<ref name="nrsCT1" /> Ionizing radiation to the head as part of treatment for other cancers is also a risk factor for developing brain cancer.<ref name="Schaff 2023" />

Mutations and deletions of [[tumor suppressor gene]]s, such as [[P53]], are thought to be the cause of some forms of brain tumor.<ref>{{cite book | vauthors=Kleihues P, Ohgaki H, Eibl RH, Reichel MB, Mariani L, Gehring M, Petersen I, Höll T, von Deimling A, Wiestler OD, Schwab M | chapter = Type and frequency of p53 mutations in tumors of the nervous system and its coverings | title = Molecular Neuro-oncology and Its Impact on the Clinical Management of Brain Tumors | pages = 25–31 | year = 1994 | publisher = Springer | isbn=978-3-540-57351-7 | series=Recent results in cancer research | volume=135}}</ref> Inherited conditions, such as [[Von Hippel–Lindau disease]], [[tuberous sclerosis]], [[multiple endocrine neoplasia]], and [[Neurofibromatosis|neurofibromatosis type 2]] carry a high risk for the development of brain tumors.<ref name=PDQ2014MD/><ref name=HodgsonNielsen2016>{{cite journal | vauthors = Hodgson TS, Nielsen SM, Lesniak MS, Lukas RV | title = Neurological Management of Von Hippel-Lindau Disease | journal = The Neurologist | volume = 21 | issue = 5 | pages = 73–8 | date = September 2016 | pmid = 27564075 | doi = 10.1097/NRL.0000000000000085 | s2cid = 29232748 | type = Review }}</ref><ref name=RogersBarani2015>{{cite journal | vauthors = Rogers L, Barani I, Chamberlain M, Kaley TJ, McDermott M, Raizer J, Schiff D, Weber DC, Wen PY, Vogelbaum MA | title = Meningiomas: knowledge base, treatment outcomes, and uncertainties. A RANO review | journal = Journal of Neurosurgery | volume = 122 | issue = 1 | pages = 4–23 | date = January 2015 | pmid = 25343186 | pmc = 5062955 | doi = 10.3171/2014.7.JNS131644 | type = Review }}</ref> People with [[celiac disease]] have a slightly increased risk of developing brain tumors.<ref name=Hourigan2006>{{cite journal | vauthors = Hourigan CS | title = The molecular basis of coeliac disease | journal = Clinical and Experimental Medicine | volume = 6 | issue = 2 | pages = 53–9 | date = June 2006 | pmid = 16820991 | doi = 10.1007/s10238-006-0095-6 | s2cid = 12795861 | type = Review }}</ref> Smoking may increase the risk, but evidence of this remains unclear.<ref>{{cite web | title=Brain Cancer Causes, Symptoms, Stages & Life Expectancy | url=https://www.medicinenet.com/brain_cancer/article.htm#do_cell_phones_cause_brain_cancer | website=MedicineNet | access-date=24 February 2020 | language=en | quote = Other risk factors such as smoking, radiation exposure, and viral infection (HIV) have been suggested but not proven to cause brain cancer.}}</ref>

Although studies have not shown any link between [[Mobile phone radiation and health|cell-phone or mobile-phone radiation]] and the occurrence of brain tumors,<ref>{{cite journal | vauthors = Frei P, Poulsen AH, Johansen C, Olsen JH, Steding-Jessen M, Schüz J | title = Use of mobile phones and risk of brain tumours: update of Danish cohort study | journal = BMJ | volume = 343 | article-number = d6387 | date = October 2011 | pmid = 22016439 | pmc = 3197791 | doi = 10.1136/bmj.d6387 }}</ref> the [[World Health Organization]] has classified mobile-phone radiation on the [[International Agency for Research on Cancer|IARC]] scale into [[List of IARC Group 2B carcinogens|Group 2B]] – possibly carcinogenic.<ref name="WHO_IARC_110531">{{cite press release |url= http://www.iarc.fr/en/media-centre/pr/2011/pdfs/pr208_E.pdf |title= IARC classifies radiofrequency electromagnetic fields as possibly carcinogenic to humans |work= [[World Health Organization]] press release N° 208 |publisher= [[International Agency for Research on Cancer]] |date= 31 May 2011 |access-date= 2 June 2011 |url-status= live |archive-url= https://web.archive.org/web/20110601063650/http://www.iarc.fr/en/media-centre/pr/2011/pdfs/pr208_E.pdf |archive-date= 1 June 2011 }}</ref>
The claim that cell-phone usage may cause brain cancer is likely based on epidemiological studies which observed a slight increase in [[glioma]] risk among heavy users of wireless phones. When those studies were conducted, GSM (2G) phones were in use. Modern, third-generation (3G) phones emit, on average, about 1% of the energy emitted by those GSM (2G) phones, and therefore the finding of an association between cell-phone usage and increased risk of brain cancer is not based upon current phone usage.<ref name=WCR2014CNS/>

==Pathophysiology==
===Meninges===
[[File:Meninges diagram.jpg|thumb|upright=1.3|The meninges lie between the skull and brain matter. Tumors originating from the meninges are meningiomas.]]
Human brains are surrounded by a system of [[connective tissue]] membranes called [[meninges]] that separate the [[Human brain|brain]] from the [[Human skull|skull]]. This three-layered covering is composed of (from the outside in) the [[dura mater]], [[arachnoid mater]], and [[pia mater]]. The arachnoid and pia are physically connected and thus often considered as a single layer, the ''leptomeninges''. Between the arachnoid mater and the pia mater is the [[subarachnoid space]] which contains [[cerebrospinal fluid]] (CSF). This fluid circulates in the narrow spaces between cells and through the cavities in the brain called [[Ventricular system|ventricles]], to support and protect the brain tissue. [[Blood vessels]] enter the [[central nervous system]] through the perivascular space above the pia mater. The cells in the blood vessel walls are joined tightly, forming the [[blood–brain barrier]] which protects the brain from [[toxins]] that might enter through the blood.<ref name=":7">{{Cite book|title=Clinically oriented anatomy| vauthors = Moore KL, Agur AM, Dalley II AF |isbn=978-1-4963-4721-3|edition= Eighth |location=Philadelphia|publisher=Lippincott Williams and Wilkins|oclc=978362025|date = September 2017}}</ref>

Tumors of the meninges are [[meningioma]]s and are often benign. Though not technically a tumor of brain tissue, they are often considered brain tumors since they protrude into the space where the brain is, causing symptoms. Since they are usually slow-growing tumors, meningiomas can be quite large by the time symptoms appear.<ref>{{Cite web|url=http://neurosurgery.ucla.edu/meningioma-brain-tumor|title=Meningioma Brain Tumor|website=neurosurgery.ucla.edu|access-date=29 July 2019}}</ref>

===Brain matter===
The three largest divisions of the brain are the [[Cerebrum|cerebral cortex]], [[cerebellum]] and the [[brainstem]].<ref name=":7" /> These areas are composed of two broad classes of cells: [[neurons]] and [[glia]]. These two cell types are equally numerous in the brain as a whole, although [[glial cells]] outnumber [[neurons]] roughly 4 to 1 in the [[cerebral cortex]]. Glia come in several types, which perform a number of critical functions, including structural support, metabolic support, insulation, and guidance of development.<ref>{{Cite web|url=https://training.seer.cancer.gov/brain/tumors/anatomy/neurons.html|title=Neurons & Glial Cells SEER Training|website=training.seer.cancer.gov|access-date=29 July 2019}}</ref> Primary tumors of the glial cells are called [[glioma]]s and often are malignant by the time they are diagnosed.<ref>{{cite journal | vauthors = Ostrom QT, Gittleman H, Farah P, Ondracek A, Chen Y, Wolinsky Y, Stroup NE, Kruchko C, Barnholtz-Sloan JS | title = CBTRUS statistical report: Primary brain and central nervous system tumors diagnosed in the United States in 2006-2010 | journal = Neuro-Oncology | volume = 15 | issue = Suppl 2 | pages = ii1-56 | date = November 2013 | pmid = 24137015 | pmc = 3798196 | doi = 10.1093/neuonc/not151 }}</ref>

The [[thalamus]] and [[hypothalamus]] are major divisions of the [[diencephalon]], with the [[pituitary gland]] and [[pineal gland]] attached at the bottom; tumors of the [[pituitary]]<ref>{{Cite web |title=Pituitary tumours |url=https://www.cancerresearchuk.org/about-cancer/brain-tumours/types/pituitary-tumours |archive-url=https://web.archive.org/web/20240301203755/https://www.cancerresearchuk.org/about-cancer/brain-tumours/types/pituitary-tumours |archive-date=1 March 2024 |access-date=18 April 2024 |website=www.cancerresearchuk.org |language=en}}</ref> and [[pineal gland]]<ref>{{Cite web |last=Kashani |first=Shayan |title=What to Know About Pineal Tumors |url=https://www.webmd.com/brain/what-to-know-about-pineal-tumors |access-date=2024-07-04 |website=WebMD |language=en}}</ref> are often benign.

The [[brainstem]] lies between the large cerebral cortex and the spinal cord. It is divided into the midbrain, pons, and medulla oblongata.<ref name=":7" />

==Diagnosis==
[[File:Postermass.png|thumb|A posterior fossa tumor leading to mass effect and midline shift]]

There are no specific signs or symptoms for brain cancer, but the presence of a combination of symptoms and the lack of alternative causes may indicate a brain tumor.<ref name="Herholz" /> A [[medical history]] aids in the diagnosis. Clinical and laboratory investigations will serve to exclude infections as the cause of the symptoms.

Brain tumors, when compared to tumors in other areas of the body, pose a challenge for diagnosis. Commonly, [[radioactive tracer]]s are uptaken in large volumes in tumors due to the high activity of tumor cells, allowing for radioactive imaging of the tumor. However, most of the brain is separated from the blood by the [[blood–brain barrier]] (BBB), a membrane that exerts a strict control over what substances are allowed to pass into the brain. Therefore, many tracers that may reach tumors in other areas of the body easily would be unable to reach brain tumors until there was a disruption of the BBB by the tumor. Disruption of the BBB is well imaged via MRI or CT scan, and is therefore regarded as the main diagnostic indicator for malignant gliomas, meningiomas, and brain metastases.<ref name="Herholz">{{cite journal | vauthors = Herholz K, Langen KJ, Schiepers C, Mountz JM | title = Brain tumors | journal = Seminars in Nuclear Medicine | volume = 42 | issue = 6 | pages = 356–70 | date = November 2012 | pmid = 23026359 | pmc = 3925448 | doi = 10.1053/j.semnuclmed.2012.06.001 }}</ref>

===Imaging===
[[File:CT brain tumor.jpg|thumb|[[CT scan]] of a brain tumor, with its diameters marked as an X. There is hypoattenuating (dark) ''peritumoral edema'' in the surrounding white matter, with a "finger-like" spread.|216x216px]]
[[Medical imaging]] plays a central role in the diagnosis of brain tumors. Early imaging methods&nbsp;– invasive and sometimes dangerous&nbsp;– such as [[pneumoencephalography]] and cerebral [[angiography]] have been replaced by non-invasive, high-resolution techniques, especially [[magnetic resonance imaging]] (MRI) and [[computed tomography]] (CT) scans.<ref name="cancer.gov">{{cite web |title=Adult Central Nervous System Tumors Treatment (PDQ®)–Patient Version – National Cancer Institute |url=https://www.cancer.gov/types/brain/patient/adult-brain-treatment-pdq |website=cancer.gov |access-date=29 January 2021 |language=en |date=11 May 2020}}</ref> MRI with contrast enhancement is the preferred imaging test in the diagnosis of brain tumors.<ref name="Schaff 2023" /><ref name=":4">{{cite journal | vauthors = Iv M, Yoon BC, Heit JJ, Fischbein N, Wintermark M | title = Current Clinical State of Advanced Magnetic Resonance Imaging for Brain Tumor Diagnosis and Follow Up | journal = Seminars in Roentgenology | volume = 53 | issue = 1 | pages = 45–61 | date = January 2018 | pmid = 29405955 | doi = 10.1053/j.ro.2017.11.005 }}</ref> Glioblastomas usually enhance with contrast on T1 MRI weighted MRI imaging, and on [[T2*-weighted imaging|T2]] with FLAIR imaging showing hyperintense cerebral edema.<ref name="Schaff 2023" /> Low grade gliomas are usually hypointense on T1 MRI, and hyperintense with T2 with FLAIR MRI. Meningiomas are usually homogenously enhanced with dural thickening on MRI.<ref name="Schaff 2023" />

Treatment with radiation can lead to treatment induced changes in the brain, including radiation necrosis (death of brain tissue due to radiation treatments) visible on brain imaging and which can be difficult to differentiate from tumor recurrence.<ref>{{cite journal |last1=Lee |first1=Dennis |last2=Riestenberg |first2=Robert A. |last3=Haskell-Mendoza |first3=Aden |last4=Bloch |first4=Orin |title=Brain Metastasis Recurrence Versus Radiation Necrosis |journal=Neurosurgery Clinics of North America |date=October 2020 |volume=31 |issue=4 |pages=575–587 |doi=10.1016/j.nec.2020.06.007 |pmid=32921353 |s2cid=221674217 }}</ref>

==== Different Types of MRI Scans ====
'''Magnetic Resonance Angiography (MRA)'''{{snd}} looks at the blood vessels in the brain. In the diagnosis of brain tumor, MRAs are typically carried out before surgery to help surgeons get a better understanding of the tumor vasculature. For example, a study was done where surgeons were able to separate benign brain tumors from malignant ones by analyzing the shapes of the blood vessels that were extracted from MRA.<ref>{{cite conference | vauthors = Bullitt E, Jung I, Muller K, Gerig G, Aylward S, Joshi S, Smith K, Lin W, Ewend M |title=Determining Malignancy of Brain Tumors by Analysis of Vessel Shape |date=2004 | doi = 10.1007/978-3-540-30136-3_79 | conference = Medical Image Computing and Computer-Assisted Intervention – MICCAI 2004 |pages=645–653 |place=Berlin, Heidelberg |publisher=Springer Berlin Heidelberg |isbn=978-3-540-22977-3 |doi-access=free }}</ref> Although not required, some MRA may inject contrast agent, gadolinium, into the patient to get an enhanced image

'''Magnetic Resonance Spectroscopy (MRS)'''{{snd}} measures the metabolic changes or chemical changes inside the tumor. The most common MRS is proton spectroscopy with its frequency measured in parts per million (ppm). Gliomas or malignant brain tumors have different spectra from normal brain tissue in that they have greater choline levels and lower N-acetyl aspartate (NAA) signals.<ref>{{cite journal | vauthors = Horská A, Barker PB | title = Imaging of brain tumors: MR spectroscopy and metabolic imaging | journal = Neuroimaging Clinics of North America | volume = 20 | issue = 3 | pages = 293–310 | date = August 2010 | pmid = 20708548 | doi = 10.1016/j.nic.2010.04.003 | pmc = 2927327 }}</ref> Using MRS in brain tumor diagnosis can help doctors identify the type of tumor and its aggressiveness. For example, benign brain tumors or meningioma have increased alanine levels. It can also help to distinguish brain tumors from scar tissues or dead tissues caused by previous radiation treatment, which does not have increased choline levels<ref>{{Cite web |title=MRI (magnetic resonance imaging) |url=https://mayfieldclinic.com/pe-mrspectroscopy.htm |access-date=2022-11-28 |website=mayfieldclinic.com |language=EN}}</ref> that brain tumors have, and from tumor-mimicking lesions such as abscesses or infarcts.

'''Perfusion Magnetic Resonance Imaging (pMRI)'''{{snd}} assess the blood volume and blood flow of different parts of the brain and brain tumors. pMRI requires the injection of contrast agent, usually gadopentetate dimeglumine (Gd-DTPA) into the veins in order to enhance the contrast. pMRI provides a cerebral blood volume map that shows the tumor vascularity and angiogenesis. Brain tumors would require a larger blood supply and thus, would show a high cerebral blood volume on the pMRI map. The vascular morphology and degree of angiogenesis from pMRI help to determine the grade and malignancy of brain tumors. For brain tumor diagnosis, pMRI is useful in determining the best site to perform biopsy and to help reduce sampling error. pMRI is also valuable for after treatment to determine if the abnormal area is a remaining tumor or a scar tissue. For patients that are undergoing anti-angiogenesis cancer therapy, pMRI can give the doctors a better sense of efficacy of the treatment by monitoring tumor cerebral blood volume.<ref>{{cite journal | vauthors = Cha S | title = Perfusion MR imaging of brain tumors | journal = Topics in Magnetic Resonance Imaging | volume = 15 | issue = 5 | pages = 279–289 | date = October 2004 | pmid = 15627003 | doi = 10.1097/00002142-200410000-00002 | s2cid = 25773559 | doi-access = free }}</ref>

'''Functional MRI (fMRI)'''{{snd}} measures blood flow changes in active parts of the brain while the patient is performing tasks and provides specific locations of the brain that are responsible for certain functions. Before performing a brain tumor surgery on patients, neurosurgeons would use fMRI to avoid damage to structures of the brain that correspond with important brain functions while resecting the tumor at the same time. Preoperative fMRI is important because it is often difficult to distinguish the anatomy near the tumor as it distorts its surrounding regions. Neurosurgeons would use fMRI to plan whether to perform a resection where tumor is surgically removed as much as possible, a biopsy where they take a surgical sampling amount to provide a diagnosis, or to not undergo surgery at all. For example, a neurosurgeon may be opposed to resecting a tumor near the motor cortex as that would affect the patient's movements. Without preoperative fMRI, the neurosurgeon would have to perform an awake-craniotomy where the patient would have to interact during open surgery to see if tumor removal would affect important brain functions.<ref>{{cite journal | vauthors = Bogomolny DL, Petrovich NM, Hou BL, Peck KK, Kim MJ, Holodny AI | title = Functional MRI in the brain tumor patient | journal = Topics in Magnetic Resonance Imaging | volume = 15 | issue = 5 | pages = 325–335 | date = October 2004 | pmid = 15627006 | doi = 10.1097/00002142-200410000-00005 | s2cid = 45995537 }}</ref>

'''Diffusion Weighted Imaging (DWI)'''{{snd}} a form of MRI that measures random Brownian motion of water molecules along a magnetic field gradient. For brain tumor diagnosis, measurement of apparent diffusion coefficient (ADC) in brain tumors allow doctors to categorize tumor type. Most brain tumors have higher ADC than normal brain tissues and doctors can match the observed ADC of the patient's brain tumor with a list of accepted ADC to identify tumor type. DWI is also useful for treatment and therapy purposes where changes in diffusion can be analyzed in response to drug, radiation, or gene therapy. Successful response results in apoptosis and increase in diffusion while failed treatment results in unchanged diffusion values.<ref>{{cite journal | vauthors = Maier SE, Sun Y, Mulkern RV | title = Diffusion imaging of brain tumors | journal = NMR in Biomedicine | volume = 23 | issue = 7 | pages = 849–864 | date = August 2010 | pmid = 20886568 | pmc = 3000221 | doi = 10.1002/nbm.1544 }}</ref>

==== Other Types of Imaging Techniques ====
'''Computed Tomography (CT) Scan'''{{snd}} uses x-rays to take pictures from different angles and computer processing to combine the pictures into a 3D image. A CT scan usually serves as an alternative to MRI in cases where the patient cannot have an MRI due to claustrophobia or pacemaker. Compared to MRI, a CT scan shows a more detailed image of the bone structures near the tumor and can be used to measure the tumor's size.<ref name=":8">{{Cite web |title=Tests for Brain and Spinal Cord Tumors in Adults |url=https://www.cancer.org/cancer/brain-spinal-cord-tumors-adults/detection-diagnosis-staging/how-diagnosed.html |access-date=2022-11-28 |website=cancer.org |language=en}}</ref> Like an MRI, a contrast dye may also be injected into the veins or ingested by mouth before a CT scan to better outline any tumors that may be present. CT scans use contrast materials that are iodine-based and barium sulfate compounds. The downside of using CT scans as opposed to MRI is that some brain tumors do not show up well on CT scans because some intra-axial masses are faint and resemble normal brain tissue. In some scenarios, brain tumors in CT scans may be mistaken for infarction, infection, and demyelination. To suspect that an intra-axial mass is a brain tumor instead of other possibilities, there must be unexplained calcifications in the brain, preservation of the cortex, and disproportionate mass effect.<ref>{{Cite web |title=Recognizing intra-axial tumors on brain computed tomography (CT) {{!}} Medmastery |url=https://public-nuxt.frontend.prod.medmastery.io/guides/brain-ct-clinical-guide/recognizing-intra-axial-tumors-brain-computed-tomography-ct-and |access-date=2022-11-28 |website=public-nuxt.frontend.prod.medmastery.io |language=en}}</ref>

'''CT Angiography (CTA)'''{{snd}} provides information about the blood vessels in the brain using X-rays. A contrast agent is always required to be injected into the patient in the CT scanner. CTA serves as an alternative to MRA.

'''Positron Emission Tomography (PET) Scan'''{{snd}} uses radiolabelled substances, such as [[Fluorodeoxyglucose|FDG]] which taken up by cells that are actively dividing. Tumor cells are more actively dividing so they would absorb more of the radioactive substance. After injection, a scanner would be used to create an image of the radioactive areas in the brain. PET scans are used more often for high-grade tumors than for low-grade tumors. It is useful after treatment to help doctors determine if the abnormal area on an MRI image is a remaining tumor or a scar tissue. Scar tissues will not show up on PET scans while tumors would.<ref name=":8" />

===Pathology===
[[File:Oligodendroglioma1 high mag.jpg|thumb|[[Micrograph]] of an [[oligodendroglioma]], a type of brain cancer. Brain [[biopsy]]. [[H&E stain]].]]
Maximal safe surgical resection (to preserve as much neurological function as possible) and histologic examination of the tumor is also required to aid in the diagnosis.<ref name="Schaff 2023" /> Cancer cells may have specific characteristics.

[[Atypia]]: an indication of abnormality of a cell (which may be indicative of malignancy). Significance of the abnormality is highly dependent on context.<ref>{{Cite journal | vauthors = Watson AN |date=2007-01-01 |title=Significance of "Atypia" Found on Needle Biopsy of the Breast: Correlation with Surgical Outcome |url=https://elischolar.library.yale.edu/ymtdl/384 |journal=Yale Medicine Thesis Digital Library}}</ref>

[[Neoplasia]]: the (uncontrolled) division of cells that is characteristic of cancer.<ref>{{cite web |title=Neoplasia |url=https://www.cancer.gov/publications/dictionaries/cancer-terms/def/neoplasm |website=www.cancer.gov |publisher=National Cancer Institute |language=en |date=2 February 2011}}</ref>

[[Necrosis]]: the (premature) death of cells, caused by external factors such as infection, toxin or trauma. Necrotic cells send the wrong chemical signals which prevent [[phagocyte]]s from disposing of the dead cells, leading to a buildup of dead tissue, cell debris and toxins at or near the site of the necrotic cells<ref name=necrs>{{MedlinePlus|002266|Necrosis}}</ref>

Local [[hypoxia (medical)|hypoxia]], or the deprivation of adequate oxygen supply to certain areas of the brain, including within the tumor, as the tumor grows and recruits local blood vessels.<ref>{{cite journal | vauthors = Emami Nejad A, Najafgholian S, Rostami A, Sistani A, Shojaeifar S, Esparvarinha M, Nedaeinia R, Haghjooy Javanmard S, Taherian M, Ahmadlou M, Salehi R, Sadeghi B, Manian M | title = The role of hypoxia in the tumor microenvironment and development of cancer stem cell: a novel approach to developing treatment | journal = Cancer Cell International | volume = 21 | issue = 1 | article-number = 62 | date = January 2021 | pmid = 33472628 | pmc = 7816485 | doi = 10.1186/s12935-020-01719-5 | doi-access = free }}</ref>

===Classification===
Tumors can be [[benign]] or [[malignant]], can occur in different parts of the brain, and may be classified as primary or secondary. A primary tumor is one that has started in the brain, as opposed to a [[metastasis|metastatic]] tumor, which is one that has spread to the brain from another area of the body.<ref>{{cite web|url=http://www.cancer.gov/cancertopics/wyntk/brain/page1|title=What you need to know about brain tumors|publisher=National Cancer Institute|archive-url=https://web.archive.org/web/20120127124137/http://www.cancer.gov/cancertopics/wyntk/brain/page1|archive-date=27 January 2012|url-status=live|access-date=25 February 2012}}</ref> The incidence of metastatic tumors is approximately four times greater than primary tumors.<ref name=Mer2012/> Tumors may or may not be [[symptomatic]]: some tumors are discovered because the patient has symptoms, others show up incidentally on an imaging scan, or at an autopsy.{{citation needed|date=December 2020}}

[[Grading of the tumors of the central nervous system]] commonly occurs on a 4-point scale (I-IV) created by the World Health Organization in 1993. Grade I tumors are the least severe and commonly associated with long-term survival, with severity and prognosis worsening as the grade increases. Low-grade tumors are often benign, while higher grades are aggressively malignant and/or metastatic. Other grading scales do exist, many based upon the same criteria as the WHO scale and graded from I-IV.<ref>{{cite journal | vauthors = Gupta A, Dwivedi T | title = A Simplified Overview of World Health Organization Classification Update of Central Nervous System Tumors 2016 | journal = Journal of Neurosciences in Rural Practice | volume = 8 | issue = 4 | pages = 629–641 | date = October 2017 | pmid = 29204027 | pmc = 5709890 | doi = 10.4103/jnrp.jnrp_168_17 | doi-access = free }}</ref>

==== Primary ====
[[File:Meningioma of the sagittal sinus isolated.jpg|thumb|Meningioma of the middle third of the sagittal sinus with large [[hyperostosis]]]]
The most common primary brain tumors are:<ref>{{Cite book|title=Meningiomas: Diagnosis, Treatment, and Outcome| vauthors = Park BJ, Kim HK, Sade B, Lee JH |publisher=Springer|year=2009|isbn=978-1-84882-910-7| veditors = Lee JH |page=11|chapter=Epidemiology}}
</ref>
* [[Gliomas]]<ref name=aans>{{cite web |title=Brain Tumors – Classifications, Symptoms, Diagnosis and Treatments |url=https://www.aans.org/en/Patients/Neurosurgical-Conditions-and-Treatments/Brain-Tumors |website=aans.org |access-date=29 January 2021 |language=en}}</ref> (50.4%)
* [[Meningiomas]]<ref name=aans/> (20.8%)
* [[Pituitary adenomas]]<ref name=aans/> (15%)
* [[Nerve sheath tumors]] (10%)

These common tumors can also be organized according to tissue of origin as shown below:<ref name="AANS 41723ct">{{cite web|url=http://www.aans.org/en/Media/Classifications-of-Brain-Tumors|title=Classifications of Brain Tumors|website=AANS|publisher=American Association of Neurological Surgeons|archive-url=https://web.archive.org/web/20170424085734/http://www.aans.org/en/Media/Classifications-of-Brain-Tumors|archive-date=24 April 2017|url-status=live|access-date=23 April 2017}}</ref>
{| class="wikitable"
|-
!
Tissue of origin
! Children !! Adults
|-
|[[Astrocytes]]||[[Pilocytic astrocytoma|Pilocytic Astrocytoma]] (PCA) ||[[Glioblastoma]]
|-
|[[Oligodendrocytes]]||  ||[[Oligodendroglioma]]
|-
|[[Ependyma]]||[[Ependymoma]]||
|-
|[[Neurons]]||[[Medulloblastoma]]||
|-
|[[Meninges]]||  ||[[Meningioma]]
|}

====Secondary====
Secondary tumors of the brain are [[metastasis|metastatic]] and have spread to the brain from [[cancer]]s originating in another organ. Metastatic spread is usually by the blood. The most common types of cancers that spread to the brain are [[lung cancer]] (accounting for over half of all cases), [[breast cancer]], [[melanoma]] skin cancer, [[kidney cancer]] and [[colon cancer]].<ref name="Brenner 2022">{{cite journal |last1=Brenner |first1=Alex W. |last2=Patel |first2=Akash J. |title=Review of Current Principles of the Diagnosis and Management of Brain Metastases |journal=Frontiers in Oncology |date=24 May 2022 |volume=12 |doi=10.3389/fonc.2022.857622|doi-access=free |pmid=35686091 |pmc=9171239 }}</ref>

=====By behavior=====
Brain tumors can be [[cancerous]] (malignant) or non-cancerous (benign). However, the definitions of malignant or benign neoplasms differ from those commonly used in other types of cancerous or non-cancerous neoplasms in the body.
In cancers elsewhere in the body, three malignant properties differentiate benign tumors from malignant forms of cancer: benign tumors are self-limited and do not invade or metastasize. Characteristics of malignant tumors include:<ref>{{cite journal | vauthors = Louis DN, Perry A, Wesseling P, Brat DJ, Cree IA, Figarella-Branger D, Hawkins C, Ng HK, Pfister SM, Reifenberger G, Soffietti R, von Deimling A, Ellison DW | title = The 2021 WHO Classification of Tumors of the Central Nervous System: a summary | journal = Neuro-Oncology | volume = 23 | issue = 8 | pages = 1231–1251 | date = August 2021 | pmid = 34185076 | pmc = 8328013 | doi = 10.1093/neuonc/noab106 }}</ref>
* uncontrolled mitosis (growth by division beyond the normal limits)
* [[anaplasia]]: the cells in the neoplasm have an obviously different form (in size and shape). Anaplastic cells display marked [[pleomorphism (cytology)|pleomorphism]]. The [[cell nuclei]] are characteristically extremely hyperchromatic (darkly stained) and enlarged; the nucleus might have the same size as the [[cytoplasm]] of the cell (nuclear-cytoplasmic ratio may approach 1:1, instead of the normal 1:4 or 1:6 ratio). [[Giant cells]] – considerably larger than their neighbors – may form and possess either one enormous nucleus or several nuclei ([[syncytium|syncytia]]). Anaplastic nuclei are variable and bizarre in size and shape.
* invasion or infiltration:
** Invasion or invasiveness is the spatial expansion of the tumor through uncontrolled mitosis, in the sense that the neoplasm invades the space occupied by adjacent tissue, thereby pushing the other tissue aside and eventually compressing the tissue. Often these tumors are associated with clearly outlined tumors in imaging.
** Infiltration is the behavior of the tumor either to grow (microscopic) tentacles that push into the surrounding tissue (often making the outline of the tumor undefined or diffuse) or to have tumor cells "seeded" into the tissue beyond the circumference of the tumorous mass.
* [[metastasis]] (spread to other locations in the body via lymph or blood).

==== By genetics ====
In 2016, the WHO restructured their classifications of some categories of [[glioma]]s to include distinct [[genetic mutations]] that have been useful in differentiating tumor types, prognoses, and treatment responses. Genetic mutations are typically detected via [[immunohistochemistry]], a technique that visualizes the presence or absence of a targeted protein via [[staining]].<ref name=":4" />
* Mutations in [[IDH1]] and [[IDH2]] genes are commonly found in low-grade gliomas
* Loss of both IDH genes combined with loss of [[chromosome]] arms 1p and 19q indicates the tumor is an [[oligodendroglioma]]<ref>{{cite web |url= https://www.lecturio.com/concepts/oligodendroglioma/| title= Oligodendroglioma|website=The Lecturio Medical Concept Library |access-date= 21 August 2021}}</ref>
* Loss of [[P53|TP53]] and [[ATRX]] characterizes [[astrocytoma]]s
* Genes [[Epidermal growth factor receptor|EGFR]], [[Telomerase reverse transcriptase|TERT]], and [[PTEN (gene)|PTEN]], are commonly altered in gliomas and are useful in differentiating tumor grade and biology<ref name=":4" />

====Specific types====
{{main|WHO classification of the tumors of the central nervous system}}
[[Anaplastic astrocytoma]], [[Anaplastic oligodendroglioma]], [[Astrocytoma]], [[Central neurocytoma]], [[Choroid plexus carcinoma]], [[Choroid plexus papilloma]], [[Choroid plexus tumor]], [[Colloid cyst]], [[Dysembryoplastic neuroepithelial tumour]], [[Ependymal tumor]], [[Fibrillary astrocytoma]], [[Giant-cell glioblastoma]], [[Glioblastoma]], [[Gliomatosis cerebri]], [[Gliosarcoma]], [[Hemangiopericytoma]], [[Medulloblastoma]], [[Medulloepithelioma]], [[Meningeal carcinomatosis]], [[Neuroblastoma]], [[Neurocytoma]], [[Oligoastrocytoma]], [[Oligodendroglioma]], [[Optic nerve sheath meningioma]], [[Pediatric ependymoma]], [[Pilocytic astrocytoma]], [[Pinealoblastoma]], [[Pineocytoma]], [[Pleomorphic anaplastic neuroblastoma]], [[Pleomorphic xanthoastrocytoma]], [[Primary central nervous system lymphoma]], [[Sphenoid wing meningioma]], [[Subependymal giant cell astrocytoma]], [[Subependymoma]], [[Trilateral retinoblastoma]].

==Treatment==
A medical team generally assesses the treatment options and presents them to the person affected and their family. Various types of treatment are available depending on tumor type and location, and may be combined to produce the best chances of survival:<ref name="aans"/>
* Surgery:<ref name="aans"/> complete or partial [[Resection (surgery)|resection]] of the tumor with the objective of removing as many tumor cells as possible.
* Radiotherapy:<ref name="aans"/> the most commonly used treatment for brain tumors; the tumor is irradiated with beta, X-rays or gamma rays.
* Chemotherapy:<ref name="aans"/> a treatment option for cancer, however, it is not always used to treat brain tumors as the blood–brain barrier can prevent some drugs from reaching the cancerous cells.
* A variety of experimental therapies are available through clinical trials.<ref>{{cite journal |last1=Huang |first1=Rui |last2=Boltze |first2=Johannes |last3=Li |first3=Shen |title=Strategies for Improved Intra-arterial Treatments Targeting Brain Tumors: a Systematic Review |journal=Frontiers in Oncology |date=26 August 2020 |volume=10 |page=1443 |doi=10.3389/fonc.2020.01443 |doi-access=free |pmid=32983974 |pmc=7479245 }}</ref><ref>{{cite journal |last1=Uluc |first1=Kutluay |last2=Neuwelt |first2=Edward A. |last3=Ambady |first3=Prakash |title=Advances in Intraarterial Chemotherapy Delivery Strategies and Blood-Brain Barrier Disruption |journal=Neurosurgery Clinics of North America |date=April 2022 |volume=33 |issue=2 |pages=219–223 |doi=10.1016/j.nec.2022.01.001 |pmid=35346454 }}</ref>

Survival rates in primary brain tumors depend on the type of tumor, age, functional status of the patient, the extent of surgical removal and other factors specific to each case.<ref>{{cite journal | vauthors = Nicolato A, Gerosa MA, Fina P, Iuzzolino P, Giorgiutti F, Bricolo A | title = Prognostic factors in low-grade supratentorial astrocytomas: a uni-multivariate statistical analysis in 76 surgically treated adult patients | journal = Surgical Neurology | volume = 44 | issue = 3 | pages = 208–21; discussion 221–3 | date = September 1995 | pmid = 8545771 | doi = 10.1016/0090-3019(95)00184-0 }}</ref>

Standard care for anaplastic oligodendrogliomas and anaplastic oligoastrocytomas is surgery followed by radiotherapy. One study found a survival benefit for the addition of chemotherapy to radiotherapy after surgery, compared with radiotherapy alone.<ref>{{cite journal | vauthors = Lecavalier-Barsoum M, Quon H, Abdulkarim B | title = Adjuvant treatment of anaplastic oligodendrogliomas and oligoastrocytomas | journal = The Cochrane Database of Systematic Reviews | issue = 5 | article-number = CD007104 | date = May 2014 | volume = 2014 | pmid = 24833028 | doi = 10.1002/14651858.cd007104.pub2 | pmc = 7388823 }}</ref>

===Surgery===
Surgical resection of the greatest extent of contrast enhancing tumor possible (gross total resection) is associated with increased overall and progression free survival in those with glioblastoma. Gross total resection is often required in other brain tumors.<ref name="Schaff 2023" /> Minimally invasive techniques are becoming the dominant trend in neurosurgical oncology.<ref>{{cite journal | vauthors = Spetzler RF, Sanai N | title = The quiet revolution: retractorless surgery for complex vascular and skull base lesions | journal = Journal of Neurosurgery | volume = 116 | issue = 2 | pages = 291–300 | date = February 2012 | pmid = 21981642 | doi = 10.3171/2011.8.JNS101896 | doi-access = free }}</ref> The main objective of surgery is to remove as many tumor cells as possible, with complete removal being the best outcome and [[cytoreduction]] ("debulking") of the tumor may otherwise be done. Due to the infiltrative nature of glioblastomas, total resection is usually unachievable and progression after surgery usually occurs, with progression occurring about 7 months after surgery.<ref name="Schaff 2023" />

Many [[meningiomas]], with the exception of some tumors located at the skull base, can be successfully removed surgically.
Most [[pituitary adenoma]]s can be removed surgically, often using a minimally invasive approach through the [[nasal cavity]] and skull base (trans-nasal, trans-sphenoidal approach). Large [[pituitary adenoma]]s require a [[craniotomy]] (opening of the skull) for their removal. Radiotherapy, including [[stereotactic]] approaches, is reserved for inoperable cases.<ref>{{cite journal | vauthors = Gheorghiu ML, Fleseriu M | title = Stereotactic Radiation Therapy in Pituitary Adenomas, is it Better than Conventional Radiation Therapy? | journal = Acta Endocrinologica | volume = 13 | issue = 4 | pages = 476–490 | date = 2017 | pmid = 31149219 | pmc = 6516550 | doi = 10.4183/aeb.2017.476 }}</ref>

Postoperative radiotherapy and chemotherapy are integral parts of the therapeutic standard for malignant tumors.<ref>{{cite journal |last1=Penoncello |first1=Gregory P. |last2=Gagneur |first2=Justin D. |last3=Vora |first3=Sujay A. |last4=Yu |first4=Nathan Y. |last5=Fatyga |first5=Mirek |last6=Mrugala |first6=Maciej M. |last7=Bendok |first7=Bernard R. |last8=Rong |first8=Yi |title=Comprehensive Commissioning and Clinical Implementation of GammaTiles STaRT for Intracranial Brain Cancer |journal=Advances in Radiation Oncology |date=July 2022 |volume=7 |issue=4 |article-number=100910 |doi=10.1016/j.adro.2022.100910 |pmid=35434425 |pmc=9010698 |s2cid=246623373 }}</ref><ref name="pmid11150363">{{cite journal | vauthors = DeAngelis LM | title = Brain tumors | journal = The New England Journal of Medicine | volume = 344 | issue = 2 | pages = 114–23 | date = January 2001 | pmid = 11150363 | doi = 10.1056/NEJM200101113440207 | issn = 0028-4793}}</ref>

Multiple metastatic tumors are generally treated with radiotherapy and chemotherapy rather than surgery and the prognosis in such cases is determined by the primary tumor, and is generally poor.{{Citation needed|date=October 2024}}

===Radiation therapy===
The goal of radiation therapy is to kill tumor cells while leaving normal brain tissue unharmed. In standard [[external beam radiation therapy]], multiple treatments of standard-dose "fractions" of radiation are applied to the brain. This process is repeated for a total of 10 to 30 treatments, depending on the type of tumor. This additional treatment provides some patients with improved outcomes and better survival rates.{{citation needed|date=December 2020}}

[[Radiosurgery]] is a treatment method that uses computerized calculations to focus radiation at the site of the tumor while minimizing the radiation dose to the surrounding brain. Radiosurgery may be an adjunct to other treatments, or it may represent the primary treatment technique for some tumors. Forms used include [[stereotactic]] radiosurgery, such as [[Gamma knife]], [[Cyberknife (device)|Cyberknife]] or [[Novalis radiosurgery|Novalis Tx]] [[radiosurgery]].<ref>{{cite web |url=http://www.sdcyberknife.com/comparison.htm |title=Radiosurgery treatment comparisons – Cyberknife, Gamma knife, Novalis Tx |access-date=22 July 2014 |archive-url=https://web.archive.org/web/20070520230154/http://www.sdcyberknife.com/comparison.htm |archive-date=20 May 2007  }}</ref>{{medrs|date=July 2014}}

[[Radiation therapy|Radiotherapy]] is the most common treatment for secondary brain tumors. The amount of radiotherapy depends on the size of the area of the brain affected by cancer. Conventional external beam "whole-brain radiotherapy treatment" (WBRT) or "whole-brain irradiation" may be suggested if there is a risk that other secondary tumors will develop in the future.<ref>{{cite web |publisher=Cancer Research UK |url=http://www.cancerhelp.org.uk/help/default.asp?page=5301 |title=Treating secondary brain tumours with WBRT |access-date=5 June 2012 |url-status=live |archive-url=https://web.archive.org/web/20071025211917/http://www.cancerhelp.org.uk/help/default.asp?page=5301 |archive-date=25 October 2007  }}</ref> Stereotactic radiotherapy is usually recommended in cases involving fewer than three small secondary brain tumors. Radiotherapy may be used following, or in some cases in place of, resection of the tumor. Forms of radiotherapy used for brain cancer include [[external beam radiation therapy]], the most common, and [[brachytherapy]] and [[proton therapy]], the last especially used for children.

People who receive stereotactic radiosurgery (SRS) and whole-brain radiation therapy (WBRT) for the treatment of metastatic brain tumors have more than twice the risk of developing learning and memory problems than those treated with SRS alone.<ref>{{cite web |publisher=MD Anderson Cancer Center |url=http://www.mdanderson.org/diseases/braincancer/display.cfm?id=8f11775f-75bb-4d7b-b3ac46878a1d56d0&method=displayfull&pn=00c8a30f-c468-11d4-80fb00508b603a14 |title=Whole Brain Radiation increases risk of learning and memory problems in cancer patients with brain metastases |access-date=5 June 2012 |archive-url=https://web.archive.org/web/20081005220401/http://www.mdanderson.org/diseases/braincancer/display.cfm?id=8f11775f-75bb-4d7b-b3ac46878a1d56d0&method=displayfull&pn=00c8a30f-c468-11d4-80fb00508b603a14 |archive-date=5 October 2008  }}</ref><ref>{{cite web |publisher=International RadioSurgery Association |url=http://www.irsa.org/metastatic_tumors.html |title=Metastatic brain tumors |access-date=5 June 2012 |archive-url=https://web.archive.org/web/20120616155755/http://www.irsa.org/metastatic_tumors.html |archive-date=16 June 2012 }}</ref> Results of a 2021 systematic review found that when using SRS as the initial treatment, survival or death related to brain metastasis was not greater than alone versus SRS with WBRT.<ref>{{cite book | vauthors = Garsa A, Jang JK, Baxi S, Chen C, Akinniranye O, Hall O, Larkin J, Motala A, Newberry S, Hempel S | title = Radiation Therapy for Brain Metasases | date = 2021-06-09 | pmid = 34152714 | doi = 10.23970/ahrqepccer242 | s2cid = 236256085 }}</ref>

Postoperative conventional daily radiotherapy improves survival for adults with good functional well-being and high grade glioma compared to no postoperative radiotherapy. Hypofractionated radiation therapy has similar efficacy for survival as compared to conventional radiotherapy, particularly for individuals aged 60 and older with [[glioblastoma]].<ref>{{cite journal | vauthors = Khan L, Soliman H, Sahgal A, Perry J, Xu W, Tsao MN | title = External beam radiation dose escalation for high grade glioma | journal = The Cochrane Database of Systematic Reviews | volume = 5 | issue = 8 | article-number = CD011475 | date = May 2020 | pmid = 32437039 | pmc = 7389526 | doi = 10.1002/14651858.CD011475.pub3 }}</ref>

===Chemotherapy===
Patients undergoing [[chemotherapy]] are administered drugs designed to kill [[tumor]] cells.<ref name="aans"/> Although chemotherapy may improve overall survival in patients with the most malignant primary brain tumors, it does so in only about 20 percent of patients. Chemotherapy is often used in young children instead of radiation, as radiation may have negative effects on the developing brain. The decision to prescribe this treatment is based on a patient's overall health, type of tumor, and extent of cancer. The toxicity and many side effects of the drugs, and the uncertain outcome of chemotherapy in brain tumors puts this treatment further down the line of treatment options with surgery and radiation therapy preferred.<ref>{{cite journal | vauthors = Perkins A, Liu G | title = Primary Brain Tumors in Adults: Diagnosis and Treatment | journal = American Family Physician | volume = 93 | issue = 3 | pages = 211–217 | date = February 2016 | pmid = 26926614 }}</ref>

UCLA Neuro-Oncology publishes real-time survival data for patients with a diagnosis of glioblastoma. They are the only institution in the United States that displays how brain tumor patients are performing on current therapies. They also show a listing of chemotherapy agents used to treat high-grade glioma tumors.<ref>{{cite web |publisher=UCLA Neuro-Oncology Program |url=http://www.neurooncology.ucla.edu/Performance/GlioblastomaMultiforme.aspx |title=How Our Patients Perform: Glioblastoma Multiforme |access-date=5 June 2012 |archive-url=https://web.archive.org/web/20120609070823/http://www.neurooncology.ucla.edu/Performance/GlioblastomaMultiforme.aspx |archive-date=9 June 2012  }}</ref>

Genetic mutations have significant effects on the effectiveness of chemotherapy. Gliomas with [[IDH1]] or [[IDH2]] mutations respond better to chemotherapy than those without the mutation. Loss of chromosome arms 1p and 19q also indicate better response to chemoradiation.<ref name=":4" />

===Other===
A [[Shunt (medical)|shunt]] may be used to relieve symptoms caused by [[intracranial pressure]], by reducing the build-up of fluid ([[hydrocephalus]]) caused by the blockage of the free flow of [[cerebrospinal fluid]].<ref>{{cite web | vauthors = Dalvi A |url= http://www.emedicinehealth.com/normal_pressure_hydrocephalus/page9_em.htm |title=Normal Pressure Hydrocephalus Causes, Symptoms, Treatment |work=eMedicineHealth |publisher=Emedicinehealth.com |access-date=17 February 2012 |url-status=live |archive-url=https://web.archive.org/web/20120222023351/http://www.emedicinehealth.com/normal_pressure_hydrocephalus/page9_em.htm |archive-date=22 February 2012  }}</ref>

For those with brain tumors, anti-seizure prophylactic (preventative) medications are not usually recommended. However, anti-epileptics are used in those with seizures.<ref name="Schaff 2023" />

Cerebral edema secondary to brain tumors is managed by corticosteroids. Dexamethasone is the preferred corticosteroid due to its long half-life and reduced effect on water retention (mineralcorticoid activity). [[Bevacizumab]] (an anti-VEGFA antibody) may improve cerebral edema in those that are unresponsive to steroids.<ref name="Schaff 2023" />

==Prognosis==
The prognosis of brain cancer depends on the type of cancer diagnosed. [[Medulloblastoma]] has a good prognosis with [[Medulloblastoma#Treatment and prognosis|chemotherapy, radiotherapy, and surgical resection]] while glioblastoma has a median survival of only 15 months even with aggressive [[chemoradiotherapy]] and surgery.<ref name=":12">{{Cite book |title=Central Nervous System Tumours |collaboration=WHO Classification of Tumours Editorial Board |publisher=International Agency for Research on Cancer |year=2021 |isbn=978-92-832-4508-7 |pages=39 ff |language=en}}</ref> Brainstem gliomas have the poorest prognosis of any form of brain cancer, with most patients dying within one year, even with therapy that typically consists of radiation to the tumor along with [[corticosteroid]]s. However, one type, focal brainstem gliomas in children, seems open to exceptional prognosis and long-term survival has frequently been reported.<ref>{{cite web |url=http://www.childhoodbraintumor.org/index.php?option=com_content&view=article&id=57:brain-stem-gliomas-in-childhood&catid=34:brain-tumor-types-and-imaging&Itemid=53 |title=Brain Stem Gliomas in Childhood |publisher=Childhoodbraintumor.org |access-date=17 February 2012 |url-status=live |archive-url=https://web.archive.org/web/20120309100048/http://www.childhoodbraintumor.org/index.php?option=com_content&view=article&id=57%3Abrain-stem-gliomas-in-childhood&catid=34%3Abrain-tumor-types-and-imaging&Itemid=53 |archive-date=9 March 2012  }}</ref>

Prognosis is also affected by presentation of genetic mutations. Certain mutations provide better prognosis than others. [[IDH1]] and [[IDH2]] mutations in [[glioma]]s, as well as deletion of chromosome arms 1p and 19q, generally indicate better prognosis. [[P53|TP53]], [[ATRX]], [[Epidermal growth factor receptor|EGFR]], [[PTEN (gene)|PTEN]], and [[Telomerase reverse transcriptase|TERT]] mutations are also useful in determining prognosis.<ref name=":4" />

===Glioblastoma===
{{Main|Glioblastoma}}

[[Glioblastoma]] is the most aggressive ([[grading of the tumors of the central nervous system|grade 4]]) and most common form of a malignant primary brain tumor. Even when aggressive multimodality therapy consisting of radiotherapy, chemotherapy, and surgical excision is used, median survival is only 15–18 months.<ref name=":12" /> Standard therapy for glioblastoma consists of maximal surgical [[Segmental resection|resection]] of the tumor, followed by radiotherapy between two and four weeks after the [[craniotomy|surgical procedure]] to remove the cancer, then by [[temozolomide|chemotherapy]], such as [[temozolomide]].<ref name=":2">{{cite journal | vauthors = Sasmita AO, Wong YP, Ling AP | title = Biomarkers and therapeutic advances in glioblastoma multiforme | journal = Asia-Pacific Journal of Clinical Oncology | volume = 14 | issue = 1 | pages = 40–51 | date = February 2018 | pmid = 28840962 | doi = 10.1111/ajco.12756 | doi-access = free }}</ref> Most patients with glioblastoma take a [[corticosteroid]], typically [[dexamethasone]], during their illness to relieve symptoms. Experimental treatments include [[targeted therapy]], [[radiosurgery#Gamma Knife|gamma knife radiosurgery]],<ref>
{{cite web |url=http://brain.mgh.harvard.edu/patientguide.htm |title=GBM Guide – MGH Brain Tumor Center |publisher=Brain.mgh.harvard.edu |access-date=17 February 2012 |url-status=live |archive-url=https://web.archive.org/web/20120216012258/http://brain.mgh.harvard.edu/PatientGuide.htm |archive-date=16 February 2012  }}
</ref> [[boron neutron capture therapy]], [[gene therapy]], and [[Carmustine#Implants|chemowafer implants]].<ref>{{cite journal |last1=Tai |first1=Chien-Kuo |last2=Kasahara |first2=Noriyuki |title=Replication-competent retrovirus vectors for cancer gene therapy |journal=Frontiers in Bioscience |date=January 2008 |volume=13 |issue=13 |pages=3083–3095 |doi=10.2741/2910 |pmid=17981778 }}</ref><ref>{{cite journal | vauthors = Murphy AM, Rabkin SD | title = Current status of gene therapy for brain tumors | journal = Translational Research | volume = 161 | issue = 4 | pages = 339–54 | date = April 2013 | pmid = 23246627 | pmc = 3733107 | doi = 10.1016/j.trsl.2012.11.003 }}</ref>

===Oligodendrogliomas===
{{Main|Oligodendroglioma}}
[[Oligodendroglioma]]s are incurable but slowly progressive malignant brain tumors. They can be treated with [[Segmental resection|surgical resection]], [[chemotherapy]], [[radiotherapy]] or a combination. For some suspected low-grade (grade II) tumors, only a course of watchful waiting and symptomatic therapy is opted for. These tumors show co-deletions of the p and q arms of [[chromosome 1 (human)|chromosome 1]] and [[chromosome 19 (human)|chromosome 19]] respectively (1p19q co-deletion) and have been found to be especially chemosensitive with one report claiming them to be one of the most chemosensitive tumors.<ref name=":12" /><ref>{{cite journal |last1=Ty |first1=A. U. |last2=See |first2=S. J. |last3=Rao |first3=J. P. |last4=Khoo |first4=J.B.K. |last5=Wong |first5=M. C. |title=Oligodendroglial tumor chemotherapy using "decreased-dose-intensity" PCV: A Singapore experience |journal=Neurology |date=24 January 2006 |volume=66 |issue=2 |pages=247–249 |doi=10.1212/01.wnl.0000194211.68164.a0 |pmid=16434664 |s2cid=31170268 }}</ref> A median survival of up to 16.7 years has been reported for grade II oligodendrogliomas.<ref>{{cite web |url=http://www.neurology.org |title=Neurology |publisher=Neurology |access-date=17 February 2012 |url-status=live |archive-url=https://web.archive.org/web/20120219094513/http://www.neurology.org/ |archive-date=19 February 2012  }}</ref>

=== Acoustic neuroma ===
[[Vestibular schwannoma|Acoustic neuroma]]s are non-cancerous tumors.<ref>{{Cite web|url=https://www.hopkinsmedicine.org/health/conditions-and-diseases/brain-tumor/vestibular-schwannoma|title=Acoustic Neuroma (Vestibular Schwannoma)|website=hopkinsmedicine.org|access-date=19 July 2019}}</ref> They can be treated with surgery, radiation therapy, or observation. Early intervention with surgery or radiation is recommended to prevent progressive hearing loss.<ref>{{Cite web|url=https://www.uptodate.com/contents/vestibular-schwannoma-acoustic-neuroma|title=UpToDate|website=uptodate.com|access-date=19 July 2019}}</ref>

==Epidemiology==
The incidence of brain tumors is higher in developed countries.<ref>{{cite journal | vauthors = Bondy ML, Scheurer ME, Malmer B, Barnholtz-Sloan JS, Davis FG, Il'yasova D, Kruchko C, McCarthy BJ, Rajaraman P, Schwartzbaum JA, Sadetzki S, Schlehofer B, Tihan T, Wiemels JL, Wrensch M, Buffler PA | title = Brain tumor epidemiology: consensus from the Brain Tumor Epidemiology Consortium | journal = Cancer | volume = 113 | issue = 7 Suppl | pages = 1953–68 | date = October 2008 | pmid = 18798534 | pmc = 2861559 | doi = 10.1002/cncr.23741 }}</ref> This could be explained by undiagnosed tumor-related deaths in resource limited or lower income countries or by early deaths caused by other poverty-related causes that preempt a patient's life before tumors develop.

The incidence of CNS tumors in the United States, Israel, and the Nordic countries is relatively high, while Japan and Asian countries have a lower incidence.<ref name=gallo>{{EMedicine|article|1156429|Low-Grade Astrocytoma}}</ref>
<!--
{{cite journal | vauthors = Crespo-Rodríguez AM, Smirniotopoulos JG, Rushing EJ | title = MR and CT imaging of 24 pleomorphic xanthoastrocytomas (PXA) and a review of the literature | journal = Neuroradiology | volume = 49 | issue = 4 | pages = 307–315 | date = April 2007 | pmid = 17205313 | doi = 10.1007/s00234-006-0191-z }}
--><ref>{{cite web |url=http://www-dep.iarc.fr |title=CANCERMondial |publisher=International Agency for Research on Cancer |access-date=17 February 2012 |url-status=live |archive-url=https://web.archive.org/web/20120217163455/http://www-dep.iarc.fr/ |archive-date=17 February 2012  }}</ref>

===United States===
In the United States in 2015, approximately 166,039 people were living with brain or other central nervous system tumors. Over 2018, it was projected that there would be 23,880 new cases of brain tumors and 16,830 deaths in 2018 as a result,<ref name=":5">{{Cite web|url=https://seer.cancer.gov/statfacts/html/brain.html|title=Cancer Stat Facts: Brain and Other Nervous System Cancer|date=31 March 2019|website=National Cancer Institute}}</ref> accounting for 1.4 percent of all cancers and 2.8 percent of all cancer deaths.<ref name=r2>{{cite web |publisher=American Cancer Society |url=http://www.cancer.org/Cancer/BrainCNSTumorsinAdults/DetailedGuide/brain-and-spinal-cord-tumors-in-adults-key-statistics |title=What are the key statistics about brain and spinal cord tumors? |date=1 May 2012 |url-status=live |archive-url=https://web.archive.org/web/20120702042112/http://www.cancer.org/Cancer/BrainCNSTumorsinAdults/DetailedGuide/brain-and-spinal-cord-tumors-in-adults-key-statistics |archive-date=2 July 2012}}</ref> Median age of diagnosis was 58 years old, while median age of death was 65. Diagnosis was slightly more common in males, at approximately 7.5 cases per 100 000 people, while females saw 2 fewer at 5.4. Deaths as a result of brain cancer were 5.3 per 100 000 for males, and 3.6 per 100 000 for females, making brain cancer the 10th leading cause of cancer death in the United States. Overall lifetime risk of developing brain cancer is approximated at 0.6 percent for men and women.<ref>{{Cite web|url=http://www.cbtrus.org/factsheet/factsheet.html|title=2018 CBTRUS Fact Sheet|date=31 March 2019|website=Central Brain Tumor Registry of the United States|access-date=14 February 2019|archive-date=14 February 2019|archive-url=https://web.archive.org/web/20190214061511/http://www.cbtrus.org/factsheet/factsheet.html}}</ref>

===UK===
Brain, other CNS or intracranial tumors are the ninth most common cancer in the UK (around 10,600 people were diagnosed in 2013), and it is the eighth most common cause of cancer death (around 5,200 people died in 2012).<ref>{{cite web|title=Brain, other CNS and intracranial tumours statistics|url=http://www.cancerresearchuk.org/cancer-info/cancerstats/types/brain/|website=Cancer Research UK|access-date=27 October 2014|url-status=live|archive-url=https://web.archive.org/web/20141016033148/http://www.cancerresearchuk.org/cancer-info/cancerstats/types/brain/|archive-date=16 October 2014}}</ref> White British patients with brain tumour are 30% more likely to die within a year of diagnosis than patients from other ethnicities.  The reason for this is unknown.<ref>[https://www.theguardian.com/science/2021/nov/09/white-british-brain-tumour-patients-more-likely-to-die-in-a-year White British brain tumour patients 'more likely to die in a year'] ''[[The Guardian]]''</ref>

===Children===
In the United States more than 28,000 people under 20 are estimated to have a brain tumor.<ref name="Quick Brain Tumor Facts">{{Cite web|url=http://braintumor.org/brain-tumor-information/brain-tumor-facts/|title=Quick Brain Tumor Facts|website=National Brain Tumor Society|access-date=14 February 2019}}</ref> About 3,720 new cases of brain tumors are expected to be diagnosed in those under 15 in 2019.<ref>{{Cite web|url=http://www.cbtrus.org/factsheet/factsheet.html|title=CBTRUS – 2018 CBTRUS Fact Sheet|website=cbtrus.org|access-date=14 February 2019|archive-date=14 February 2019|archive-url=https://web.archive.org/web/20190214061511/http://www.cbtrus.org/factsheet/factsheet.html}}</ref> Higher rates were reported in 1985–1994 than in 1975–1983. There is some debate as to the reasons; one theory is that the trend is the result of improved diagnosis and reporting, since the jump occurred at the same time that [[Magnetic resonance imaging|MRIs]] became available widely, and there was no coincident jump in [[Mortality rate|mortality]]. Central nervous system tumors make up 20–25 percent of cancers in children.<ref name=":6">{{Cite journal| vauthors = Hoda SA, Cheng E |date=6 November 2017|title=Robbins Basic Pathology|journal=American Journal of Clinical Pathology |volume=148 |issue=6 |page=557 |doi=10.1093/ajcp/aqx095 |doi-access=free}}</ref><ref name="r2" /><ref>{{cite journal | vauthors = Chamberlain MC, Kormanik PA | title = Practical guidelines for the treatment of malignant gliomas | journal = The Western Journal of Medicine | volume = 168 | issue = 2 | pages = 114–120 | date = February 1998 | pmid = 9499745 | pmc = 1304839 }}</ref>

The average survival rate for all primary brain cancers in children is 74%.<ref name="Quick Brain Tumor Facts"/> Brain cancer is the most common cancer in children under 19 and results in more deaths in this age group than [[leukemia]].<ref>{{Cite web|url=http://fortune.com/2016/09/16/cancer-in-children-deaths/|title=Childhood Brain Cancer Now Leads to More Deaths than Leukemia|website=Fortune|access-date=14 February 2019}}</ref> Younger people have worse prognoses.<ref>{{cite web |url=http://seer.cancer.gov/publications/childhood/cns.pdf |title=CNS and Miscellaneous Intracranial and Intraspinal Neoplasms |access-date=4 December 2008 |vauthors=Gurney JG, Smith MA, Bunin GR |work=SEER Pediatric Monograph |publisher=[[National Cancer Institute]] |pages=51–57 |quote=In the US, approximately 2,200 children and adolescents younger than 20 years of age are diagnosed with malignant central nervous system tumors each year. More than 90 percent of primary CNS malignancies in children are located within the brain. |url-status=live |archive-url=https://web.archive.org/web/20081217044133/http://seer.cancer.gov/publications/childhood/cns.pdf |archive-date=17 December 2008  }}</ref>

The most common brain tumor types in children (0–14) are: [[pilocytic astrocytoma]], [[Glioma|malignant glioma]], [[medulloblastoma]], neuronal and mixed neuronal-glial tumors, and [[ependymoma]].<ref>{{cite web |url=https://www.lecturio.com/concepts/ependymoma/| title=Ependymoma|website=The Lecturio Medical Concept Library |access-date= 19 July 2021}}</ref>

In children under 2, about 70% of brain tumors are [[medulloblastoma]]s, [[ependymoma]]s, and low-grade [[glioma]]s. Less commonly, and seen usually in infants, are [[teratoma]]s and [[ATRT|atypical teratoid rhabdoid tumor]]s.<ref>{{cite web |url=http://www.childhoodbraintumor.org/brain-tumor-types-and-imaging/163-infantile-brain-tumors.html |title=Infantile Brain Tumors | vauthors = Rood BR |publisher=The Childhood Brain Tumor Foundation |access-date=23 July 2014 |url-status=live |archive-url=https://web.archive.org/web/20121111030047/http://www.childhoodbraintumor.org/brain-tumor-types-and-imaging/163-infantile-brain-tumors.html |archive-date=11 November 2012  }}</ref> [[Germ cell tumor]]s, including teratomas, make up just 3% of pediatric primary brain tumors, but the worldwide incidence varies significantly.<ref name=pmid18586924>{{cite journal | vauthors = Echevarría ME, Fangusaro J, Goldman S | title = Pediatric central nervous system germ cell tumors: a review | journal = The Oncologist | volume = 13 | issue = 6 | pages = 690–9 | date = June 2008 | pmid = 18586924 | doi = 10.1634/theoncologist.2008-0037 | s2cid = 8114229 | doi-access = free }}</ref>

In the UK, 429 children aged 14 and under are diagnosed with a brain tumour on average each year, and 563 children and young people under the age of 19 are diagnosed.<ref>{{cite web|url=https://www.thebraintumourcharity.org/understanding-brain-tumours/symptoms-and-information/childhood-brain-tumours/|title=About childhood brain tumours|access-date=16 June 2016|url-status=live|archive-url=https://web.archive.org/web/20160807085945/https://www.thebraintumourcharity.org/understanding-brain-tumours/symptoms-and-information/childhood-brain-tumours/|archive-date=7 August 2016}}</ref>

==Research==
===Immunotherapy===
[[Cancer immunotherapy]] is being actively studied. For malignant gliomas no therapy has been shown to improve life expectancy as of 2015.<ref>{{cite book | vauthors = Bloch O | title = Current Understanding and Treatment of Gliomas | chapter = Immunotherapy for Malignant Gliomas | series = Cancer Treatment and Research | volume = 163 | pages = 143–158 | date = 2015 | pmid = 25468230 | doi = 10.1007/978-3-319-12048-5_9 | isbn = 978-3-319-12047-8 }}</ref>

===Vesicular stomatitis virus===
{{See also|Oncolytic virus}}
In 2000, researchers used the [[vesicular stomatitis virus]] (VSV) to infect and kill cancer cells without affecting healthy cells.<ref>{{cite journal | vauthors = Auer R, Bell JC | title = Oncolytic viruses: smart therapeutics for smart cancers | journal = Future Oncology | volume = 8 | issue = 1 | pages = 1–4 | date = January 2012 | pmid = 22149027 | doi = 10.2217/fon.11.134 }}</ref><ref>{{cite journal | vauthors = Garber K | title = China approves world's first oncolytic virus therapy for cancer treatment | journal = Journal of the National Cancer Institute | volume = 98 | issue = 5 | pages = 298–300 | date = March 2006 | pmid = 16507823 | doi = 10.1093/jnci/djj111 | doi-access = free }}</ref>

===Retroviral replicating vectors===
[[File:Tumor BrainstemGlioma2.JPG|thumb|A [[brainstem glioma]] in four-year-old. MRI, [[sagittal]], without contrast]]
Led by Prof. Nori Kasahara, researchers from [[University of Southern California|USC]], who are now at [[University of California, Los Angeles|UCLA]], reported in 2001 the first successful example of applying the use of [[Viral vector|retroviral replicating vectors]] towards transducing cell lines derived from solid tumors.<ref>{{cite journal | vauthors = Logg CR, Tai CK, Logg A, Anderson WF, Kasahara N | title = A uniquely stable replication-competent retrovirus vector achieves efficient gene delivery in vitro and in solid tumors | journal = Human Gene Therapy | volume = 12 | issue = 8 | pages = 921–32 | date = May 2001 | pmid = 11387057 | doi = 10.1089/104303401750195881 | pmc = 8184367 }}</ref> Building on this initial work, the researchers applied the technology to ''in vivo'' models of cancer and in 2005 reported a long-term survival benefit in an experimental brain tumor animal model.<ref>{{cite journal | vauthors = Tai CK, Wang WJ, Chen TC, Kasahara N | title = Single-shot, multicycle suicide gene therapy by replication-competent retrovirus vectors achieves long-term survival benefit in experimental glioma | journal = Molecular Therapy | volume = 12 | issue = 5 | pages = 842–51 | date = November 2005 | pmid = 16257382 | doi = 10.1016/j.ymthe.2005.03.017 | pmc = 8185609 | doi-access = free }}</ref>{{medrs|date=July 2014}}  Subsequently, in preparation for human clinical trials, this technology was further developed by Tocagen (a pharmaceutical company primarily focused on brain cancer treatments) as a combination treatment ([[Toca 511 & Toca FC]]). This has been under investigation since 2010 in a Phase I/II clinical trial for the potential treatment of recurrent high-grade glioma including glioblastoma and anaplastic astrocytoma. No results have yet been published.<ref>{{ClinicalTrialsGov|NCT01156584|A Study of a Retroviral Replicating Vector Combined With a Prodrug Administered to Patients With Recurrent Malignant Glioma}}</ref>

===Non-invasive detection===
Efforts to detect and monitor development and treatment response of brain tumors by liquid biopsy from blood, cerebrospinal fluid or urine, are in the early stages of development.<ref>{{cite journal | vauthors = van der Pol Y, Mouliere F | title = Toward the Early Detection of Cancer by Decoding the Epigenetic and Environmental Fingerprints of Cell-Free DNA | journal = Cancer Cell | volume = 36 | issue = 4 | pages = 350–368 | date = October 2019 | pmid = 31614115 | doi = 10.1016/j.ccell.2019.09.003 | doi-access = free }}</ref><ref name="pmid34771592">{{cite journal | vauthors = Eibl RH, Schneemann M | title = Liquid Biopsy and Primary Brain Tumors | journal = Cancers (Basel) | volume = 13 | issue = 21 | date = October 2021 | page = 5429 | pmid = 34771592 | pmc = 8582521 | doi = 10.3390/cancers13215429 | doi-access = free }}</ref>

== See also ==
* [[Brain]]
* [[Tumor]]
* [[Nervous system neoplasm]]
* [[List of people with brain tumors]]

== References ==
{{Reflist}}

== External links ==
{{Medical resources
| medlinePlus_mult= {{MedlinePlus2|000768}}
|  ICD10          = {{ICD10|C|71}}, {{ICD10|D|33}},
|  ICD9           = {{ICD9|191}}, {{ICD9|225.0}}
|  ICDO           =
|  OMIM           =
| DiseasesDB=30781
|  MedlinePlus    = 007222
|  eMedicineSubj  = emerg
|  eMedicineTopic = 334
|  MeshID         = D001932
}}
{{commons category|Brain tumors}}
* [https://www.cancerresearchuk.org/about-cancer/brain-tumours Brain tumour information] from [[Cancer Research UK]]
* [https://web.archive.org/web/20120618110047/http://www.bccancer.bc.ca/HPI/CancerManagementGuidelines/NeuroOncology/default.htm Neuro-Oncology:] Cancer Management Guidelines
* [https://web.archive.org/web/20110922103733/http://rad.usuhs.edu/medpix/kiosk_image.html?pt_id=13381&imageid=52032 MedPix Teaching File] MR Scans of Primary Brain Lymphoma, etc.

{{Nervous tissue tumors}}
{{Tumors}}

{{Authority control}}

[[Category:Brain tumor| ]]
[[Category:Disorders causing seizures]]
[[Category:Wikipedia medicine articles ready to translate]]
[[Category:Tumors]]