View source for Stomach cancer

{{Short description|Cancerous tumor originating in the stomach lining}}
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{{Use dmy dates|date=February 2024}}
{{Infobox medical condition (new)
| name            = Stomach cancer
| synonyms        = Gastric cancer
| image           = Linitis plastica 2.jpg
| caption         = Endoscopic image of [[linitis plastica]], a type of stomach cancer where the entire [[stomach]] is invaded, leading to a leather bottle-like appearance with [[bleeding|blood]] coming out of it
| field           = [[Gastroenterology]] [[Oncology]]
| symptoms        = '''Early''': {{hlist|[[Heartburn]]|[[bloating]]|upper [[abdominal pain]]|[[nausea]]|[[Burping|belching]]|[[Anorexia (symptom)|loss of appetite]]<ref name=NCI2014TxPt/>}}'''Later''': {{hlist|[[Weight loss]]|[[jaundice|yellowing of the skin and whites of the eyes]]|[[hematemesis|vomiting blood]]|[[Dysphagia|difficulty swallowing]]|[[Melena|blood in the stool]]<ref name=NCI2014TxPt/>}}
| complications   =
| onset           = Over years<ref name=WCR2014/>
| duration        =
| types           = Gastric carcinomas, [[lymphoma]], [[mesenchymal tumor]]<ref name=WCR2014/>
| causes          = ''[[Helicobacter pylori]]'', [[genetics]]<ref name=WCR2014/><ref name=ChangParsonnet2010/>
| risks           = Smoking, alcohol, dietary factors such as [[pickled vegetables]], [[obesity]]<ref name=WCR2014/><ref name=pmid24011243/>
| diagnosis       = [[Biopsy]] done during [[endoscopy]]<ref name=NCI2014TxPt/>
| differential    =
| prevention      = [[Mediterranean diet]], not smoking<ref name=WCR2014/><ref name=NCI2014Prevent/>
| treatment       = Surgery, [[chemotherapy]], [[radiation therapy]], [[targeted therapy]]<ref name=NCI2014TxPt/>
| medication      =
| prognosis       =  [[Five-year survival rate]]:<br />< 10% (advanced cases),<ref name = WJG14/><br />32% (US),<ref name=SEER2020/> 71% (Japan)<ref name=Jap2011/>
| frequency       = 968,350 (2022)<!-- incidence -->.<ref name="Bray2022">{{Cite journal |last1=Bray |first1=Freddie |last2=Laversanne |first2=Mathieu |last3=Sung |first3=Hyuna |last4=Ferlay |first4=Jacques |last5=Siegel |first5=Rebecca L. |last6=Soerjomataram |first6=Isabelle |last7=Jemal |first7=Ahmedin |date=2024-04-04 |title=Global cancer statistics 2022: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries |journal=CA: A Cancer Journal for Clinicians |volume=74 |issue=3 |pages=229–263 |language=en |doi=10.3322/caac.21834 |issn=0007-9235|doi-access=free |pmid=38572751 }}</ref> It happens when [[cancer]] cells develop in the lining of the stomach (also called the gastric mucosa). These cancer cells have the ability to invade or spread ([[metastasise]]) to other parts of the body.
| deaths          = 659,853 (2022)<ref name="Bray2022" />
|alt=}}
<!-- Definition and Symptoms -->
'''Stomach cancer''', also known as '''gastric cancer''', is a [[malignant tumor]] of the stomach. It is a [[cancer]] that develops in the [[Gastric mucosa|lining of the stomach]], caused by abnormal cell growth.<ref>{{cite web|title=Stomach (Gastric) Cancer|url=http://www.cancer.gov/cancertopics/types/stomach|website=NCI|access-date=1 July 2014|url-status=live|archive-url=https://web.archive.org/web/20140704181619/http://www.cancer.gov/cancertopics/types/stomach|archive-date=4 July 2014|date=January 1980}}</ref> Most cases of stomach cancers are gastric [[carcinomas]], which can be divided into several subtypes, including gastric [[adenocarcinomas]].<ref name=WCR2014/> [[Lymphomas]] and [[mesenchymal tumors]] may also develop in the stomach.<ref name=WCR2014/> Early symptoms may include [[heartburn]], upper abdominal pain, [[nausea]], and [[Anorexia (symptom)|loss of appetite]].<ref name=NCI2014TxPt/> Later signs and symptoms may include [[weight loss]], [[jaundice|yellowing of the skin and whites of the eyes]], [[Hematemesis|vomiting]], [[Dysphagia|difficulty swallowing]], and [[Melena|blood in the stool]], among others.<ref name="NCI2014TxPt">{{cite web|title=Gastric Cancer Treatment (PDQ®)|url=http://www.cancer.gov/cancertopics/pdq/treatment/gastric/Patient/page1/AllPages|website=NCI|access-date=1 July 2014|date=17 April 2014|url-status=live|archive-url=https://web.archive.org/web/20140705231337/http://www.cancer.gov/cancertopics/pdq/treatment/gastric/Patient/page1/AllPages|archive-date=5 July 2014}}</ref> The cancer may [[metastasis|spread]] from the stomach to other parts of the body, particularly the [[liver]], [[lungs]], [[bone]]s, [[peritoneum|lining of the abdomen]], and [[lymph node]]s.<ref>{{cite book| vauthors = Ruddon RW |title=Cancer biology|date=2007|publisher=Oxford University Press|isbn=978-0-19-517543-1|page=223|edition=4th|url=https://books.google.com/books?id=PymZ1ORk0TcC&pg=PA223|url-status=live|archive-url=https://web.archive.org/web/20150915231411/https://books.google.com/books?id=PymZ1ORk0TcC&pg=PA223|archive-date=15 September 2015}}</ref>

<!-- Cause and Diagnosis -->
The [[bacterium]] ''[[Helicobacter pylori]]'' accounts for more than 60% of cases of stomach cancer.<ref name=WCR2014/><ref name=ChangParsonnet2010>{{cite journal | vauthors = Chang AH, [[Julie Parsonnet|Parsonnet J]] | title = Role of bacteria in oncogenesis | journal = Clinical Microbiology Reviews | volume = 23 | issue = 4 | pages = 837–857 | date = October 2010 | pmid = 20930075 | pmc = 2952975 | doi = 10.1128/CMR.00012-10 }}</ref><ref>{{cite book| veditors = Sim F, McKee M |title=Issues in public health |date=2011 |publisher=Open University Press |isbn=978-0-335-24422-5 |page=74 |edition=2nd|url=https://books.google.com/books?id=Jn8xC6_UW8YC&pg=PA74}}</ref> Certain strains of ''H. pylori'' have greater risks than others.<ref name=WCR2014/> Smoking, dietary factors such as [[pickled vegetables]] and [[obesity]] are other risk factors.<ref name="WCR2014" /><ref name="pmid24011243">{{cite journal | vauthors = González CA, Sala N, Rokkas T | title = Gastric cancer: epidemiologic aspects | journal = Helicobacter | volume = 18 | issue = Suppl 1 | pages = 34–38 | date = September 2013 | pmid = 24011243 | doi = 10.1111/hel.12082 | s2cid = 22918077 | doi-access = free }}</ref> About 10% of cases run in families, and between 1% and 3% of cases are due to [[Cancer syndrome|genetic syndromes]] [[Heredity|inherited]] such as [[hereditary diffuse gastric cancer]].<ref name=WCR2014/> Most of the time, stomach cancer develops in stages over the years.<ref name=WCR2014/> Diagnosis is usually by [[biopsy]] done during [[endoscopy]].<ref name=NCI2014TxPt/> This is followed by [[medical imaging]] to determine if the cancer has spread to other parts of the body.<ref name=NCI2014TxPt/> [[Japan]] and [[South Korea]], two countries that have high rates of the disease, [[cancer screening|screen for stomach cancer]].<ref name=WCR2014/>

<!--Prevention, treatment and prognosis -->
A [[Mediterranean diet]] lowers the risk of stomach cancer, as does not smoking.<ref name=WCR2014/><ref name=NCI2014Prevent/> Tentative evidence indicates that treating ''[[Helicobacter pylori|H. pylori]]'' decreases the future risk.<ref name=WCR2014/><ref name=NCI2014Prevent>{{cite web|title=Stomach (Gastric) Cancer Prevention (PDQ®)|url=http://www.cancer.gov/cancertopics/pdq/prevention/gastric/HealthProfessional|website=NCI|access-date=1 July 2014|date=27 February 2014|url-status=live|archive-url=https://web.archive.org/web/20140704195947/http://www.cancer.gov/cancertopics/pdq/prevention/gastric/HealthProfessional|archive-date=4 July 2014}}</ref> If stomach cancer is treated early, it can be cured.<ref name=WCR2014/> Treatments may include some combination of surgery, [[chemotherapy]], [[radiation therapy]], and [[targeted therapy]].<ref name=NCI2014TxPt/><ref name=Wagner17>{{cite journal | vauthors = Wagner AD, Syn NL, Moehler M, Grothe W, Yong WP, Tai BC, Ho J, Unverzagt S | title = Chemotherapy for advanced gastric cancer | journal = The Cochrane Database of Systematic Reviews | volume = 2017 | article-number = CD004064 | date = August 2017 | issue = 8 | pmid = 28850174 | pmc = 6483552 | doi = 10.1002/14651858.cd004064.pub4 }}</ref> For certain subtypes of gastric cancer, [[cancer immunotherapy]] is an option as well.<ref>{{cite journal | vauthors = Kodach LL, Peppelenbosch MP | title = Targeting the Myeloid-Derived Suppressor Cell Compartment for Inducing Responsiveness to Immune Checkpoint Blockade Is Best Limited to Specific Subtypes of Gastric Cancers | journal = Gastroenterology | volume = 161 | issue = 2 | page = 727 | date = August 2021 | pmid = 33798523 | doi = 10.1053/j.gastro.2021.03.047 | doi-access = free }}</ref> If treated late, [[palliative care]] may be advised.<ref name=WCR2014/> Some types of lymphoma can be cured by eliminating ''H. pylori''.<ref name=St2010>{{cite journal | vauthors = Stathis A, Bertoni F, Zucca E | title = Treatment of gastric marginal zone lymphoma of MALT type | journal = Expert Opinion on Pharmacotherapy | volume = 11 | issue = 13 | pages = 2141–2152 | date = September 2010 | pmid = 20586708 | doi = 10.1517/14656566.2010.497141 | s2cid = 6796557 }}</ref> Outcomes are often poor, with a less than 10% [[five-year survival rate]] in the Western world for advanced cases.<ref name = WJG14/><!-- Quote = In Western countries, about two-thirds of gastric cancer patients are diagnosed with locally advanced or metastatic disease. Median survival for these patients is around 10 months, and less than 10% survive at 5 years. --> This is largely because most people with the condition present with advanced disease.<ref name=WJG14>{{cite journal | vauthors = Orditura M, Galizia G, Sforza V, Gambardella V, Fabozzi A, Laterza MM, Andreozzi F, Ventriglia J, Savastano B, Mabilia A, Lieto E, Ciardiello F, De Vita F | title = Treatment of gastric cancer | journal = World Journal of Gastroenterology | volume = 20 | issue = 7 | pages = 1635–1649 | date = February 2014 | pmid = 24587643 | pmc = 3930964 | doi = 10.3748/wjg.v20.i7.1635 | doi-access = free }}</ref> In the United States, five-year survival is 31.5%,<ref name=SEER2020>{{cite web|url=https://seer.cancer.gov/statfacts/html/stomach.html|title=Cancer of the Stomach - Cancer Stat Facts|website=SEER|language=en|access-date=1 February 2020}}</ref> while in South Korea it is over 65% and Japan over 70%, partly due to screening efforts.<ref name=WCR2014/><ref name=Jap2011>{{cite web |title=がん診療連携拠点病院等院内がん登録生存率集計: [国立がん研究センター がん登録・統計] |url=https://ganjoho.jp/reg_stat/statistics/brochure/hosp_c_reg_surv.html |website=ganjoho.jp |access-date=2 February 2020}}</ref>

<!-- Epidemiology -->
Globally, stomach cancer is the fifth-leading type of cancer and the third-leading cause of death from cancer, making up 7% of cases and 9% of deaths.<ref name=WCR2014Epi>{{cite book| vauthors = Stewart BW, Wild C | collaboration = International Agency for Research on Cancer |author4=World Health Organization|title=World Cancer Report 2014|date=2014|publisher=World Health Organization|isbn=978-92-832-0429-9|chapter=1.1 The global and regional burden of cancer |ref={{harvid|World Cancer Report 2014}}}}</ref> In 2018, it newly occurred in 1.03 million people and caused 783,000 deaths.<ref name=Bray2018>{{cite journal | vauthors = Bray F, Ferlay J, Soerjomataram I, Siegel RL, Torre LA, Jemal A | title = Global cancer statistics 2018: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries | journal = CA: A Cancer Journal for Clinicians| volume = 68 | issue = 6 | pages = 394–424 | date = November 2018 | pmid = 30207593 | doi = 10.3322/caac.21492 | s2cid = 52188256 | doi-access = free }}</ref> Before the 1930s, it was a leading cause of cancer deaths in the [[Western countries|Western world]];  rates have sharply declined among younger generations in the West,  although they remain high for people living in East Asia.<ref>{{cite book| vauthors = Tobias SJ, Hochhauser D, Souhami RL |title=Cancer and its management|date=2010|publisher=Wiley-Blackwell|isbn=978-1-4443-0637-8|page=259|edition=6th|url=https://books.google.com/books?id=9sW0eCoZFt4C&pg=PA259 }}</ref><ref>{{cite book| veditors = Khleif RT, Skeel SN |title=Handbook of cancer chemotherapy|date=2011|publisher=Wolter Kluwer|isbn=978-1-60831-782-0|page=127|edition=8th|url=https://books.google.com/books?id=6Nz_87OLrtcC&pg=PA127}}</ref><ref>{{cite book| vauthors = Knight JA |title=Human Longevity: The Major Determining Factors|date=2010|publisher=Author House|isbn=978-1-4520-6722-3|page=339|url=https://books.google.com/books?id=HBY_GxOY_6oC&pg=PA339|url-status=live|archive-url=https://web.archive.org/web/20150916003533/https://books.google.com/books?id=HBY_GxOY_6oC&pg=PA339|archive-date=16 September 2015}}{{self-published inline|date=August 2023}}</ref> The decline in the West is believed to be due to the decline of salted and pickled food consumption, as a result of the development of [[refrigeration]] as a method of preserving food.<ref>{{cite book| veditors = Moore RJ, Spiegel D |title=Cancer, culture, and communication|date=2004|publisher=Kluwer Academic|isbn=978-0-306-47885-7|page=[https://archive.org/details/springer_10.1007-b105731/page/n157 139]|url=https://archive.org/details/springer_10.1007-b105731}}</ref> Stomach cancer occurs most commonly in [[East Asia]], followed by [[Eastern Europe]].<ref name=WCR2014/> It occurs twice as often in males as in females.<ref name=WCR2014>{{cite book|title={{harvnb|World Cancer Report 2014}}|date=2014|chapter=5.4 Stomach Cancer}}</ref>

==Signs and symptoms==
[[File:Por-sig.jpg|thumb|right|Endoscopic images of the stomach [[cancer]] in early stage. Its histology was poorly differentiated [[adenocarcinoma]] with [[signet ring cells]]. Left above: normal, right above: FICE, left low: acetate stained, right low: AIM stained]]
[[File:Linitis plastica.jpg|thumb|right| Endoscopic image of [[linitis plastica]], where the entire [[stomach]] is invaded with cancer, leading to a leather bottle like appearance and congealed pus and blood]]
Stomach cancer is often either [[asymptomatic]] (producing no noticeable symptoms) or it may cause only [[nonspecific symptoms]] (which may also be present in other related or unrelated disorders) in its early stages. By the time symptoms are recognized, the cancer has often reached an advanced stage (see below) and may have metastasized (spread to other, perhaps distant, parts of the body), which is one of the main reasons for its relatively poor prognosis.<ref name="SAOGC">{{cite web|url=http://www.cancerresearchuk.org/cancer-help/type/stomach-cancer/treatment/statistics-and-outlook-for-stomach-cancer|title=Statistics and outlook for stomach cancer|publisher=Cancer Research UK|access-date=19 February 2014|url-status=live|archive-url=https://web.archive.org/web/20140105105505/http://www.cancerresearchuk.org/cancer-help/type/stomach-cancer/treatment/statistics-and-outlook-for-stomach-cancer|archive-date=5 January 2014}}</ref> Stomach cancer can cause the following signs and symptoms: Unexplained nausea, vomiting, diarrhoea, and constipation. Patients can also experience unexplained weight loss.<ref>{{cite journal | vauthors = Al-Azri M, Al-Kindi J, Al-Harthi T, Al-Dahri M, Panchatcharam SM, Al-Maniri A | title = Awareness of Stomach and Colorectal Cancer Risk Factors, Symptoms and Time Taken to Seek Medical Help Among Public Attending Primary Care Setting in Muscat Governorate, Oman | journal = Journal of Cancer Education | volume = 34 | issue = 3 | pages = 423–434 | date = June 2019 | pmid = 28782080 | doi = 10.1007/s13187-017-1266-8 | s2cid = 4017466 }}</ref>

Early cancers may be associated with [[indigestion]] or a burning sensation ([[heartburn]]). However, fewer than one in every 50 people referred for endoscopy due to indigestion has cancer.<ref>{{cite web |url=http://www.dh.gov.uk/prod_consum_dh/groups/dh_digitalassets/@dh/@en/documents/digitalasset/dh_4080278.pdf |title=Guidance on Commissioning Cancer Services Improving Outcomes in Upper Gastro-intestinal Cancers |publisher=NHS |date=Jan 2001 |archive-url=https://web.archive.org/web/20121013060159/http://www.dh.gov.uk/prod_consum_dh/groups/dh_digitalassets/@dh/@en/documents/digitalasset/dh_4080278.pdf |archive-date=13 October 2012 }}</ref> [[Abdominal pain|Abdominal discomfort]] and [[loss of appetite]] can occur.<ref>{{Cite web|url=https://www.nhs.uk/conditions/stomach-cancer/symptoms/|title=Symptoms of stomach cancer|date=17 September 2018|website=nhs.uk}}</ref><ref>{{cite journal | vauthors = Ehret C, Jatoi A | title = Should Loss of Appetite Be Palliated in Patients with Advanced Cancer? | journal = Current Treatment Options in Oncology | volume = 22 | issue = 4 | page = 31 | date = February 2021 | pmid = 33641020 | pmc = 7914034 | doi = 10.1007/s11864-021-00829-0 }}</ref>

Gastric cancers that have enlarged and invaded normal tissue can cause [[weakness]], [[fatigue (physical)|fatigue]], [[bloating]] of the stomach after meals, [[abdominal pain]] in the upper abdomen, [[nausea]] and occasional [[vomiting]]. Further enlargement may cause [[weight loss]] or [[bleeding]] with [[vomiting blood]] or having [[blood in the stool]], the latter apparent as black discolouration ([[melena]]) and sometimes leading to [[anemia]]. [[Dysphagia]] suggests a tumour in the [[cardia]] or extension of the gastric tumour into the [[esophagus]].{{citation needed|date=May 2021}}

These can be symptoms of other problems such as a [[stomach virus]], [[gastric ulcer]], or [[tropical sprue]].{{citation needed|date=May 2021}}

==Risk factors==
Gastric cancer can occur as a result of many factors.<ref>{{cite journal | vauthors = Lee YY, Derakhshan MH | title = Environmental and lifestyle risk factors of gastric cancer | journal = Archives of Iranian Medicine | volume = 16 | issue = 6 | pages = 358–365 | date = June 2013 | pmid = 23725070 | doi = <!-- 013166/AIM.0010 --> | url = http://www.ams.ac.ir/AIM/NEWPUB/13/16/6/0010.pdf | access-date = 3 May 2019 | archive-url = https://web.archive.org/web/20200918232240/http://www.ams.ac.ir/AIM/NEWPUB/13/16/6/0010.pdf | archive-date = 18 September 2020 }}</ref> It occurs twice as commonly in males as females. [[Estrogen]] may protect women against the development of this form of cancer.<ref>{{cite journal | vauthors = Chandanos E, Lagergren J | title = Oestrogen and the enigmatic male predominance of gastric cancer | journal = European Journal of Cancer | volume = 44 | issue = 16 | pages = 2397–2403 | date = November 2008 | pmid = 18755583 | doi = 10.1016/j.ejca.2008.07.031 }}</ref><ref>{{cite journal | vauthors = Qin J, Liu M, Ding Q, Ji X, Hao Y, Wu X, Xiong J | title = The direct effect of estrogen on cell viability and apoptosis in human gastric cancer cells | journal = Molecular and Cellular Biochemistry | volume = 395 | issue = 1–2 | pages = 99–107 | date = October 2014 | pmid = 24934239 | doi = 10.1007/s11010-014-2115-2 | s2cid = 14288660 }}</ref>

===Infections===
''[[Helicobacter pylori]]'' infection is an essential risk factor in 65–80% of gastric cancers, but only 2% of people with ''H. pylori'' infections develop stomach cancer.<ref name="pmid24011243" /><ref name="GVRF-4">{{cite web |url=https://www.who.int/vaccine_research/documents/en/gvrf2003.pdf |title=Proceedings of the fourth Global Vaccine Research Forum |date=April 2004 |work=Initiative for Vaccine Research team of the Department of Immunization, Vaccines and Biologicals |publisher=WHO |quote=Epidemiology of ''Helicobacter pylori'' and gastric cancer... |access-date=11 May 2009 |archive-url=https://web.archive.org/web/20090727175108/http://www.who.int/vaccine_research/documents/en/gvrf2003.pdf |archive-date=27 July 2009 }}</ref> The mechanism by which ''H. pylori'' induces stomach cancer potentially involves chronic inflammation, the action of ''H. pylori'' virulence factors such as [[CagA]],<ref name="pmid16367902">{{cite journal | vauthors = Hatakeyama M, Higashi H | title = Helicobacter pylori CagA: a new paradigm for bacterial carcinogenesis | journal = Cancer Science | volume = 96 | issue = 12 | pages = 835–843 | date = December 2005 | pmid = 16367902 | doi = 10.1111/j.1349-7006.2005.00130.x | s2cid = 5721063 | doi-access = free | pmc = 11159386 }}</ref> or an interaction between ''H. pylori'' infection and germline pathogenic variants in homologous-recombination genes.<ref>{{cite journal | vauthors = Usui Y, Taniyama Y, Endo M, Koyanagi YN, Kasugai Y, Oze I, Ito H, Imoto I, Tanaka T, Tajika M, Niwa Y, Iwasaki Y, Aoi T, Hakozaki N, Takata S, Suzuki K, Terao C, Hatakeyama M, Hirata M, Sugano K, Yoshida T, Kamatani Y, Nakagawa H, Matsuda K, Murakami Y, Spurdle AB, Matsuo K, Momozawa Y | title = ''Helicobacter pylori'', Homologous-Recombination Genes, and Gastric Cancer | journal = The New England Journal of Medicine | volume = 388 | issue = 13 | pages = 1181–1190 | date = March 2023 | pmid = 36988593 | doi = 10.1056/NEJMoa2211807 | s2cid = 257804097 }}</ref> It was estimated that [[Epstein–Barr virus]] is responsible for 84,000 cases per year.<ref>{{cite web |url=http://www.cancerresearchuk.org/about-us/cancer-news/press-release/2014-03-24-developing-a-vaccine-for-the-epstein-barr-virus-could-prevent-up-to-200000-cancers-globally-say |title=Developing a vaccine for the Epstein–Barr Virus could prevent up to 200,000 cancers globally say experts |website=Cancer Research UK |date= 24 March 2014|access-date=17 March 2017 |url-status=live |archive-url=https://web.archive.org/web/20170319073808/http://www.cancerresearchuk.org/about-us/cancer-news/press-release/2014-03-24-developing-a-vaccine-for-the-epstein-barr-virus-could-prevent-up-to-200000-cancers-globally-say |archive-date=19 March 2017 }}</ref> [[AIDS]] is also associated with elevated risk.<ref name="pmid24011243"/>

===Smoking===
Smoking increases the risk of developing gastric cancer significantly, from a 40% increased risk for people who currently smoke to an 82% increase for people who smoke heavily. Gastric cancers due to smoking mostly occur in the upper part of the stomach near the esophagus.<ref name=ACS_Risk/><ref>{{cite journal | vauthors = Nomura A, Grove JS, Stemmermann GN, Severson RK | title = Cigarette smoking and stomach cancer | journal = Cancer Research | volume = 50 | issue = 21 | page = 7084 | date = November 1990 | pmid = 2208177 | url = http://cancerres.aacrjournals.org/cgi/pmidlookup?view=long&pmid=2208177 }}</ref><ref>{{cite journal | vauthors = Trédaniel J, Boffetta P, Buiatti E, Saracci R, Hirsch A | title = Tobacco smoking and gastric cancer: review and meta-analysis | journal = International Journal of Cancer | volume = 72 | issue = 4 | pages = 565–573 | date = August 1997 | pmid = 9259392 | doi = 10.1002/(SICI)1097-0215(19970807)72:4<565::AID-IJC3>3.0.CO;2-O | s2cid = 42758668 | doi-access = free }}</ref>

===Alcohol===
Some studies show [[Alcohol and cancer|increased risk with alcohol consumption]] as well.<ref name="pmid24011243"/><ref name="pmid24191271">{{cite journal | vauthors = Thrumurthy SG, Chaudry MA, Hochhauser D, Mughal M | title = The diagnosis and management of gastric cancer | journal = BMJ | volume = 347 | issue = 16 | article-number = f6367 | date = November 2013 | pmid = 24191271 | doi = 10.1136/bmj.f6367 | s2cid = 16351105 }}</ref>

===Diet===
Dietary factors are not proven causes, and the association between stomach cancer and various foods and beverages is weak.<ref name="Theodoratou2017">{{cite journal | vauthors = Theodoratou E, Timofeeva M, Li X, Meng X, Ioannidis JP | title = Nature, Nurture, and Cancer Risks: Genetic and Nutritional Contributions to Cancer | journal = Annual Review of Nutrition | volume = 37 | pages = 293–320 | date = August 2017 | pmid = 28826375 | pmc = 6143166 | doi = 10.1146/annurev-nutr-071715-051004 | type = Review }}</ref> Some foods including [[fried foods]],<ref>{{cite journal |vauthors=Zhang T, Song SS, Liu M, Park S |title=Association of Fried Food Intake with Gastric Cancer Risk: A Systemic Review and Meta-Analysis of Case-Control Studies |journal=Nutrients |volume=15 |issue=13 |date=June 2023 |page=2982 |pmid=37447308 |pmc=10347084 |doi=10.3390/nu15132982 |doi-access=free |url=}}</ref> [[smoked foods]], [[salt]] and [[Low sodium diet#High sodium content|salt-rich foods]], [[meat]],<ref name=ferro-meat>{{cite journal |vauthors=Ferro A, Rosato V, Rota M, Costa AR, Morais S, Pelucchi C, Johnson KC, Hu J, Palli D, Ferraroni M, Zhang ZF, Bonzi R, Yu GP, Peleteiro B, López-Carrillo L, Tsugane S, Hamada GS, Hidaka A, Zaridze D, Maximovitch D, Vioque J, Navarrete-Munoz EM, Aragonés N, Martín V, Hernández-Ramírez RU, Bertuccio P, Ward MH, Malekzadeh R, Pourfarzi F, Mu L, López-Cervantes M, Persiani R, Kurtz RC, Lagiou A, Lagiou P, Boffetta P, Boccia S, Negri E, Camargo MC, Curado MP, La Vecchia C, Lunet N |title=Meat intake and risk of gastric cancer in the Stomach cancer Pooling (StoP) project |journal=Int J Cancer |volume=147 |issue=1 |pages=45–55 |date=July 2020 |pmid=31584199 |pmc=8550819 |doi=10.1002/ijc.32707 |url=}}</ref> [[processed meat]],<ref name=ferro-meat /> [[red meat]],<ref name=ferro-meat /> [[pickled vegetables]], and [[bracken]]s<ref>{{cite journal | vauthors = Alonso-Amelot ME, Avendaño M | title = Human carcinogenesis and bracken fern: a review of the evidence | journal = Current Medicinal Chemistry | volume = 9 | issue = 6 | pages = 675–686 | date = March 2002 | pmid = 11945131 | doi = 10.2174/0929867023370743 | url = http://www.benthamdirect.org/pages/content.php?CMC/2002/00000009/00000006/0004C.SGM | archive-url = https://web.archive.org/web/20111006102621/http://www.benthamdirect.org/pages/content.php?CMC%2F2002%2F00000009%2F00000006%2F0004C.SGM | archive-date = 6 October 2011 | url-access = subscription }}</ref> are [[association (statistics)|associated]] with a higher risk of stomach cancer.<ref name="pmid24011243"/><ref name="pmid16865769">{{cite journal | vauthors = Jakszyn P, Gonzalez CA | title = Nitrosamine and related food intake and gastric and oesophageal cancer risk: a systematic review of the epidemiological evidence | journal = World Journal of Gastroenterology | volume = 12 | issue = 27 | pages = 4296–4303 | date = July 2006 | pmid = 16865769 | pmc = 4087738 | doi = 10.3748/wjg.v12.i27.4296 | doi-access = free }}</ref>

Fresh fruit and vegetable intake,<ref name=ferro-fruits>{{cite journal |vauthors=Ferro A, Costa AR, Morais S, Bertuccio P, Rota M, Pelucchi C, Hu J, Johnson KC, Zhang ZF, Palli D, Ferraroni M, Yu GP, Bonzi R, Peleteiro B, López-Carrillo L, Tsugane S, Hamada GS, Hidaka A, Malekzadeh R, Zaridze D, Maximovich D, Vioque J, Navarrete-Muñoz EM, Alguacil J, Castaño-Vinyals G, Wolk A, Håkansson N, Hernández-Ramírez RU, Pakseresht M, Ward MH, Pourfarzi F, Mu L, López-Cervantes M, Persiani R, Kurtz RC, Lagiou A, Lagiou P, Boffetta P, Boccia S, Negri E, Camargo MC, Curado MP, La Vecchia C, Lunet N |title=Fruits and vegetables intake and gastric cancer risk: A pooled analysis within the Stomach cancer Pooling Project |journal=Int J Cancer |volume=147 |issue=11 |pages=3090–3101 |date=December 2020 |pmid=32525569 |doi=10.1002/ijc.33134 |pmc=8545605 |url=|hdl=10216/143193 |hdl-access=free }}</ref> citrus fruit intake,<ref name=ferro-fruits /> and [[antioxidant]] intake are associated with a lower risk of stomach cancer.<ref name="pmid24011243"/><ref name=ACS_Risk>{{cite web|url=http://www.cancer.org/cancer/stomachcancer/detailedguide/stomach-cancer-risk-factors|title=What Are The Risk Factors For Stomach Cancer(Website)|publisher=American Cancer Society|access-date=31 March 2010|url-status=live|archive-url=https://web.archive.org/web/20100706014402/http://www.cancer.org/Cancer/StomachCancer/DetailedGuide/stomach-cancer-risk-factors|archive-date=6 July 2010}}</ref> A Mediterranean diet is associated with lower rates of stomach cancer,<ref name="American Journal of Clinical Nutrition">{{cite journal | vauthors = Buckland G, Agudo A, Luján L, Jakszyn P, Bueno-de-Mesquita HB, Palli D, Boeing H, Carneiro F, Krogh V, Sacerdote C, Tumino R, Panico S, Nesi G, Manjer J, Regnér S, Johansson I, Stenling R, Sanchez MJ, Dorronsoro M, Barricarte A, Navarro C, Quirós JR, Allen NE, Key TJ, Bingham S, Kaaks R, Overvad K, Jensen M, Olsen A, Tjønneland A, Peeters PH, Numans ME, Ocké MC, Clavel-Chapelon F, Morois S, Boutron-Ruault MC, Trichopoulou A, Lagiou P, Trichopoulos D, Lund E, Couto E, Boffeta P, Jenab M, Riboli E, Romaguera D, Mouw T, González CA | title = Adherence to a Mediterranean diet and risk of gastric adenocarcinoma within the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort study | journal = The American Journal of Clinical Nutrition | volume = 91 | issue = 2 | pages = 381–390 | date = February 2010 | pmid = 20007304 | doi = 10.3945/ajcn.2009.28209 | doi-access = free }}</ref> as is regular [[aspirin]] use.<ref name="pmid24011243"/>

Obesity is a physical risk factor that has been found to increase the risk of gastric adenocarcinoma by contributing to the development of [[gastroesophageal reflux disease]] (GERD).<ref name="crew">{{cite journal | vauthors = Crew KD, Neugut AI | title = Epidemiology of gastric cancer | journal = World Journal of Gastroenterology | volume = 12 | issue = 3 | pages = 354–362 | date = January 2006 | pmid = 16489633 | pmc = 4066052 | doi = 10.3748/wjg.v12.i3.354 | doi-access = free }}</ref> The exact mechanism by which obesity causes GERD is not completely known. Studies hypothesize that increased dietary fat, leading to increased pressure on the stomach and the lower esophageal sphincter, due to excess adipose tissue, could play a role, yet no statistically significant data have been collected.<ref name="hamp">{{cite journal | vauthors = Hampel H, Abraham NS, El-Serag HB | title = Meta-analysis: obesity and the risk for gastroesophageal reflux disease and its complications | journal = Annals of Internal Medicine | volume = 143 | issue = 3 | pages = 199–211 | date = August 2005 | pmid = 16061918 | doi = 10.7326/0003-4819-143-3-200508020-00006 | s2cid = 15540274 | doi-access =  }}</ref> However, the risk of gastric cardia adenocarcinoma, with GERD present, has been found to increase more than two times for an obese person.<ref name="crew"/> There is a correlation between [[iodine deficiency]] and gastric cancer.<ref>{{cite book| vauthors = Josefssson M, Ekblad E |year=2009 |pages=215–220|chapter=22. Sodium Iodide Symporter (NIS) in Gastric Mucosa: Gastric Iodide Secretion |title=Comprehensive Handbook of Iodine: Nutritional, Biochemical, Pathological and Therapeutic Aspects | veditors = Preedy VR, Burrow GN, Watson R |isbn=978-0-12-374135-6 |publisher=Elsevier}}</ref>
===Genetics===
About 10% of cases run in families, and between 1 and 3% of cases are due to [[genetic syndrome]]s [[Heredity|inherited]] such as [[hereditary diffuse gastric cancer]].<ref name=WCR2014/>

A genetic risk factor for gastric cancer is a genetic defect of the [[CDH1 (gene)|''CDH1'' gene]] known as [[hereditary diffuse gastric cancer]] (HDGC). The ''CDH1'' gene, which codes for E-cadherin, lies on the 16th chromosome.<ref name="chel"/> When the gene experiences a particular mutation, gastric cancer develops through a mechanism that is not fully understood.<ref name="chel">{{cite web|url=http://www.nostomachforcancer.org/gastric-cancer/hereditary-diffuse-gastric-cancer|title=Hereditary Diffuse Cancer|website=No Stomach for Cancer|access-date=21 October 2014|url-status=live|archive-url=https://web.archive.org/web/20141020042257/http://www.nostomachforcancer.org/gastric-cancer/hereditary-diffuse-gastric-cancer|archive-date=20 October 2014}}</ref><ref>{{cite journal | vauthors = Kulmambetova G, Shtefanov I, Aitkulova A, Imanbekova M, Iskakova A, Makishev A, Ramankulov Y | title = Association of polymorphisms in TP53 and the promoter region of IL10 with gastric cancer in a Kazakh population | journal = Bosnian Journal of Basic Medical Sciences | volume = 20 | issue = 4 | pages = 539–546 | date = November 2020 | pmid = 32651972 | pmc = 7664782 | doi = 10.17305/bjbms.2020.4761 }}</ref> This mutation is considered autosomal dominant, meaning that half of a carrier's children will likely experience the same mutation.<ref name="chel"/> Diagnosis of hereditary diffuse gastric cancer usually takes place when at least two cases involving a family member, such as a parent or grandparent, are diagnosed, with at least one diagnosed before the age of 50.<ref name="chel"/> The diagnosis can also be made if at least three cases occur in the family, in which case age is not considered.<ref name="chel"/>

The [[International Cancer Genome Consortium]] is leading efforts to identify [[genome|genomic]] changes involved in stomach cancer.<ref name="ICGC-USA">{{cite web|url=http://www.icgc.org/icgc/cgp/69/509/70268|title=Gastric Cancer — Adenocarcinoma|publisher=International Cancer Genome Consortium|access-date=24 February 2014|url-status=live|archive-url=https://web.archive.org/web/20140421063815/http://icgc.org/icgc/cgp/69/509/70268|archive-date=21 April 2014}}</ref><ref name="ICGC-China">{{cite web|url=http://www.icgc.org/icgc/cgp/69/371/811|title=Gastric Cancer—Intestinal- and diffuse-type|publisher=International Cancer Genome Consortium|access-date=24 February 2014|url-status=live|archive-url=https://web.archive.org/web/20140207190902/http://icgc.org/icgc/cgp/69/371/811|archive-date=7 February 2014}}</ref> A very small percentage of diffuse-type gastric cancers (see Histopathology below) arise from an [[heredity|inherited]] abnormal ''[[CDH1 (gene)|CDH1]]'' [[gene]]. [[Genetic testing]] and treatment options are available for families at risk.<ref name="pmid15235021">{{cite journal | vauthors = Brooks-Wilson AR, Kaurah P, Suriano G, Leach S, Senz J, Grehan N, Butterfield YS, Jeyes J, Schinas J, Bacani J, Kelsey M, Ferreira P, MacGillivray B, MacLeod P, Micek M, Ford J, Foulkes W, Australie K, Greenberg C, LaPointe M, Gilpin C, Nikkel S, Gilchrist D, Hughes R, Jackson CE, Monaghan KG, Oliveira MJ, Seruca R, Gallinger S, Caldas C, Huntsman D | title = Germline E-cadherin mutations in hereditary diffuse gastric cancer: assessment of 42 new families and review of genetic screening criteria | journal = Journal of Medical Genetics | volume = 41 | issue = 7 | pages = 508–517 | date = July 2004 | pmid = 15235021 | pmc = 1735838 | doi = 10.1136/jmg.2004.018275 }}</ref>

===Bile reflux===

[[Bile reflux]], in addition to ''[[Helicobacter pylori]]'' infection, is a pathogenic factor in gastric [[intestinal metaplasia]], a precancerous lesion of gastric cancer.<ref>{{cite journal |vauthors=Qu X, Shi Y |title=Bile reflux and bile acids in the progression of gastric intestinal metaplasia |journal=Chin Med J (Engl) |volume=135 |issue=14 |pages=1664–1672 |date=July 2022 |pmid=35940882 |doi=10.1097/CM9.0000000000002290 |url=|pmc=9509189 }}</ref>  Long-term irritation of the gastric mucosa caused by bile reflux appears to have a role in gastric carcinogenesis.<ref name = Lei2023>{{cite journal |vauthors=Lei X, Cui ZY, Huang XJ |title=Exploration of gastric carcinogenesis from the relationship between bile acids and intestinal metaplasia and intragastric microorganisms (H. pylori and non-H. pylori) |journal=J Cancer Res Clin Oncol |volume=149 |issue=18 |pages=16947–16956 |date=December 2023 |pmid=37707577 |doi=10.1007/s00432-023-05407-5 |url=|pmc=11797623 }}</ref>  [[Bile acid]]s, which are a significant component of bile reflux, may be a causal factor in gastric carcinogenesis.<ref name = Lei2023/>

==Diagnosis==
[[File:Adenocarcinoma of the stomach.jpg|thumb|A [[stomach ulcer]] that was diagnosed as cancer on [[biopsy]]]]
To find the cause of symptoms, the doctor asks about the patient's medical history, does a physical examination, and may order laboratory studies.<ref>{{cite web |url=https://www.lecturio.com/concepts/gastric-cancer/| title=Gastric Cancer
|website=The Lecturio Medical Concept Library |access-date= 22 July 2021}}</ref>
The patient may also have one or all of these exams:
* [[Gastroscopic exam]] is the diagnostic method of choice. This involves insertion of a [[fibre optic]] camera into the stomach to visualise it.<ref name="pmid24191271"/>
* [[Upper GI series]] (may be called barium roentgenogram)
* [[Computed tomography]] or CT scanning of the abdomen may reveal gastric cancer. It is more useful to determine invasion into adjacent tissues or the presence of spread to local lymph nodes. Wall thickening of more than 1&nbsp;cm that is focal, eccentric, and enhancing favours malignancy.<ref>{{cite journal | vauthors = Virmani V, Khandelwal A, Sethi V, Fraser-Hill M, Fasih N, Kielar A | title = Neoplastic stomach lesions and their mimickers: spectrum of imaging manifestations | journal = Cancer Imaging | volume = 12 | pages = 269–278 | date = August 2012 | issue = 1 | pmid = 22935192 | pmc = 3458788 | doi = 10.1102/1470-7330.2012.0031 }}</ref>

In 2013, Chinese and Israeli scientists reported a successful [[pilot study]] of a [[breathalyzer]]-style breath test intended to diagnose stomach cancer by analyzing exhaled chemicals without the need for an intrusive [[endoscopy]].<ref>{{cite journal | vauthors = Xu ZQ, Broza YY, Ionsecu R, Tisch U, Ding L, Liu H, Song Q, Pan YY, Xiong FX, Gu KS, Sun GP, Chen ZD, Leja M, Haick H | title = A nanomaterial-based breath test for distinguishing gastric cancer from benign gastric conditions | journal = British Journal of Cancer | volume = 108 | issue = 4 | pages = 941–950 | date = March 2013 | pmid = 23462808 | pmc = 3590679 | doi = 10.1038/bjc.2013.44 }}</ref><ref>{{cite web|url=http://www.medicalnewstoday.com/articles/257245.php|date=6 March 2013|access-date=11 March 2022|publisher=Medical News Today| vauthors = Paddock C |title=Breath Test Could Detect And Diagnose Stomach Cancer}}</ref> A larger-scale [[clinical trial]] of this technology was completed in 2014.<ref>{{cite journal | vauthors = Amal H, Leja M, Funka K, Skapars R, Sivins A, Ancans G, Liepniece-Karele I, Kikuste I, Lasina I, Haick H | title = Detection of precancerous gastric lesions and gastric cancer through exhaled breath | journal = Gut | volume = 65 | issue = 3 | pages = 400–407 | date = March 2016 | pmid = 25869737 | doi = 10.1136/gutjnl-2014-308536 | s2cid = 206961387 | url = https://dspace.lu.lv/dspace/handle/7/31137 }}</ref><ref>{{cite journal | vauthors = Wang L, Li J, Xiong X, Hao T, Zhang C, Gao Z, Zhong L, Zhao Y | title = Volatile organic compounds as a potential screening tool for neoplasm of the digestive system: a meta-analysis | journal = Scientific Reports | volume = 11 | issue = 1 | page = 23716 | date = December 2021 | pmid = 34887450 | pmc = 8660806 | doi = 10.1038/s41598-021-02906-8 | bibcode = 2021NatSR..1123716W }}</ref>

Abnormal tissue seen in a gastroscope examination is [[biopsy|biopsied]] by the [[surgery|surgeon]] or [[gastroenterologist]]. This tissue is then sent to a [[pathology|pathologist]] for [[histology|histological]] examination under a microscope to check for the presence of cancerous cells. A biopsy, with subsequent histological analysis, is the only sure way to confirm the presence of cancer cells.<ref name="pmid24191271"/>

Various gastroscopic modalities have been developed to increase the yield of detected mucosa with a dye that accentuates the cell structure and can identify areas of dysplasia. Endocytoscopy involves ultra-high magnification to visualise cellular structure to better determine areas of dysplasia. Other gastroscopic modalities such as [[optical coherence tomography]] are being tested investigatively for similar applications.<ref>{{cite journal | vauthors = Inoue H, Kudo SE, Shiokawa A | title = Technology insight: Laser-scanning confocal microscopy and endocytoscopy for cellular observation of the gastrointestinal tract | journal = Nature Clinical Practice. Gastroenterology & Hepatology | volume = 2 | issue = 1 | pages = 31–37 | date = January 2005 | pmid = 16265098 | doi = 10.1038/ncpgasthep0072 | s2cid = 34445155 }}</ref>

Several [[cutaneous condition|skin conditions]] are associated with gastric cancer. A condition of darkened [[hyperplasia]] of the skin, frequently of the [[axilla]] and groin, known as [[acanthosis nigricans]], is associated with intra-abdominal cancers such as gastric cancer. Other cutaneous manifestations of gastric cancer include "tripe palms" (a similar darkening hyperplasia of the skin of the palms) and the [[Leser-Trelat sign]], which is the rapid development of skin lesions known as [[seborrheic keratosis|seborrheic keratoses]].<ref name="pmid15230897">{{cite journal | vauthors = Pentenero M, Carrozzo M, Pagano M, Gandolfo S | title = Oral acanthosis nigricans, tripe palms and sign of leser-trélat in a patient with gastric adenocarcinoma | journal = International Journal of Dermatology | volume = 43 | issue = 7 | pages = 530–532 | date = July 2004 | pmid = 15230897 | doi = 10.1111/j.1365-4632.2004.02159.x | s2cid = 37434568 }}</ref>

Various blood tests may be done, including a [[Complete Blood Count|complete blood count]]  to check for anaemia, and a [[Fecal occult blood|fecal occult blood test]] to check for blood in the stool.<ref>{{cite journal |vauthors=Beg M, Singh M, Saraswat MK, Rewari BB |year=2002 |title=Occult Gastrointestinal Bleeding: Detection, Interpretation, and Evaluation |url=http://medind.nic.in/jac/t02/i2/jact02i2p153.pdf |journal=JIACM |volume=3 |issue=2 |pages=153–58 |url-status=live |archive-url=https://web.archive.org/web/20101122112908/http://medind.nic.in/jac/t02/i2/jact02i2p153.pdf |archive-date=22 November 2010 }}</ref>

===Histopathology===
[[File:Pie chart of stomach cancer types by relative incidence.png|thumb|Stomach cancer types by relative incidence<ref>{{cite journal | vauthors = Parsonnet J, Friedman GD, Vandersteen DP, Chang Y, Vogelman JH, Orentreich N, Sibley RK | title = ''Helicobacter pylori'' infection and the risk of gastric carcinoma | journal = The New England Journal of Medicine | volume = 325 | issue = 16 | pages = 1127–1131 | date = October 1991 | pmid = 1891020 | doi = 10.1056/NEJM199110173251603 | doi-access = free }}</ref>]]
* ''Gastric [[adenocarcinoma]]'' is a malignant epithelial tumour, originating from glandular epithelium of the gastric mucosa. Stomach cancers are about 90% [[adenocarcinomas]].<ref>{{cite book | vauthors = Robbins SL, Cotran RS, Kuma V   |title=Pathologic Basis of Disease |edition=8th |page=784 |publisher=Saunders Elsevier |year=2010 |isbn=978-1-4160-3121-5 }}</ref> Histologically, there are two major types of gastric adenocarcinoma ([[Lauren classification]]): intestinal type or diffuse type. Adenocarcinomas tend to aggressively invade the gastric wall, infiltrating the [[muscularis mucosae]], the [[submucosa]], and then the [[muscularis propria]]. Intestinal-type adenocarcinoma tumour cells describe irregular tubular structures, harbouring pluristratification, multiple lumens, and reduced stroma ("back to back" aspect). Often, it is associated with intestinal metaplasia in neighbouring mucosa. Depending on glandular architecture, cellular pleomorphism, and mucosecretion, adenocarcinoma may present 3 degrees of differentiation: well, moderate, and poorly differentiated. [[Linitis plastica|Diffuse type]] adenocarcinoma (mucinous, colloid, [[linitis plastica]] or leather-bottle stomach) tumour cells are discohesive and secrete mucus, which is delivered in the interstitium, producing large pools of mucus/colloid (optically "empty" spaces). It is poorly differentiated. In [[signet ring cell carcinoma]]s, the mucus remains inside the tumour cell and pushes the nucleus to the periphery, giving rise to [[signet-ring cell]]s.{{citation needed|date=May 2021}}
* Around 5% of gastric cancers are lymphomas.<ref>{{cite book |last=Kumar |title=Pathologic Basis of Disease |edition=8th |page=786 |publisher=Saunders Elsevier |year=2010 |isbn=978-1-4160-3121-5 |display-authors=etal}}</ref> These may include [[Marginal zone B-cell lymphoma#Extranodal marginal zone lymphoma|extranodal marginal zone B-cell lymphomas]] (MALT type)<ref name=Bur2017>{{cite journal | vauthors = Burkitt MD, Duckworth CA, Williams JM, Pritchard DM | title = Helicobacter pylori-induced gastric pathology: insights from in vivo and ex vivo models | journal = Disease Models & Mechanisms | volume = 10 | issue = 2 | pages = 89–104 | date = February 2017 | pmid = 28151409 | pmc = 5312008 | doi = 10.1242/dmm.027649 }}</ref> and to a lesser extent [[diffuse large B-cell lymphoma]]s.<ref name="pmid25052386">{{cite journal | vauthors = Qu Q, Xuan W, Fan GH | title = Roles of resolvins in the resolution of acute inflammation | journal = Cell Biology International | volume = 39 | issue = 1 | pages = 3–22 | date = January 2015 | pmid = 25052386 | doi = 10.1002/cbin.10345 | s2cid = 10160642 }}</ref> MALT type make up about half of stomach lymphomas.<ref name=St2010/>
* [[Carcinoid]] and stromal tumors may occur.{{citation needed|date=May 2021}}

<gallery widths="180px" heights="140px">
File:Adenocarcinoma low differentiated (stomach) H&E magn 400x.jpg|Poor to moderately differentiated adenocarcinoma of the stomach. [[H&E stain]].
File:Gastric signet ring cell carcinoma histopatholgy (1).jpg|Gastric [[signet ring cell carcinoma]]. [[H&E stain]].
File:Gastric adenocarcinoma.jpg|Adenocarcinoma of the stomach and [[intestinal metaplasia]]. [[H&E stain]].
</gallery>

===Staging===
[[File:Diagram showing the T stages of stomach cancer CRUK 374.svg|thumb|right|T stages of stomach cancer]]
If cancer cells are found in the tissue sample, the next step is to [[cancer staging|stage]], or find out the extent of the disease. Various tests determine whether the cancer has spread, and if so, what parts of the body are affected. Because stomach cancer can spread to the liver, pancreas, and other organs near the stomach, as well as to the lungs, the doctor may order a [[CT scan]], a [[PET scan]],<ref name="pmid16418249">{{cite journal | vauthors = Lim JS, Yun MJ, Kim MJ, Hyung WJ, Park MS, Choi JY, Kim TS, Lee JD, Noh SH, Kim KW | title = CT and PET in stomach cancer: preoperative staging and monitoring of response to therapy | journal = Radiographics | volume = 26 | issue = 1 | pages = 143–156 | year = 2006 | pmid = 16418249 | doi = 10.1148/rg.261055078 | url = https://ir.ymlib.yonsei.ac.kr/handle/22282913/109524 }}</ref> an [[endoscopic ultrasound]] exam, or other tests to check these areas. Blood tests for [[tumor marker]]s, such as [[carcinoembryonic antigen]] and carbohydrate antigen, may be ordered, as their levels correlate with the extent of metastasis, especially to the liver, and the cure rate.{{citation needed|date=May 2021}}

Staging may not be complete until after surgery. The surgeon removes nearby lymph nodes and possibly samples of tissue from other areas in the abdomen for examination by a pathologist.{{citation needed|date=May 2021}}

The clinical stages of stomach cancer are:<ref>{{cite web|url=http://www.cancer.org/docroot/cri/content/cri_2_4_4x_treatment_choices_by_type_and_stage_of_stomach_cancer_40.asp|title=Detailed Guide: Stomach Cancer Treatment Choices by Type and Stage of Stomach Cancer|date=3 November 2009|publisher=American Cancer Society|url-status=live|archive-url=https://web.archive.org/web/20091008105442/http://www.cancer.org/docroot/cri/content/cri_2_4_4x_treatment_choices_by_type_and_stage_of_stomach_cancer_40.asp|archive-date=8 October 2009}}</ref><ref>{{cite web|url=http://www.ehealthmd.com/library/stomachcancer/STC_stages.html|title=What Are The Stages Of Stomach Cancer?| vauthors = Slowik G |date=October 2009|publisher=ehealthmd.com|url-status=live|archive-url=https://web.archive.org/web/20100102013902/http://ehealthmd.com/library/stomachcancer/STC_stages.html|archive-date=2 January 2010}}</ref>
* '''Stage 0''' – Limited to the inner lining of the stomach, it is treatable by endoscopic mucosal resection when found very early (in routine screenings), or otherwise by [[gastrectomy]] and [[lymphadenectomy]] without need for chemotherapy or radiation.
* '''Stage I''' –   Penetration to the second or third layers of the stomach (stage 1A) or to the second layer and nearby [[lymph nodes]] (stage 1B): Stage 1A is treated by surgery, including removal of the [[Greater omentum|omentum]]. Stage 1B may be treated with chemotherapy ([[5-fluorouracil]]) and radiation therapy.
* '''Stage II''' – Penetration to the second layer and more distant lymph nodes, or the third layer and only nearby lymph nodes, or all four layers but not the lymph nodes, it is treated as for stage I, sometimes with additional [[Adjuvant chemotherapy#Neoadjuvant therapy|neoadjuvant chemotherapy]].
* '''Stage III''' – Penetration to the third layer and more distant lymph nodes, or penetration to the fourth layer and either nearby tissues or nearby or more distant lymph nodes, it is treated as for stage II; a cure is still possible in some cases.
* '''Stage IV''' – Cancer has spread to nearby tissues and more distant lymph nodes, or has [[metastasize]]d to other organs. A cure is very rarely possible at this stage. Some other techniques to prolong life or improve symptoms are used, including laser treatment, surgery, and/or stents to keep the digestive tract open, and chemotherapy by drugs such as 5-fluorouracil, [[cisplatin]], [[epirubicin]], [[etoposide]], [[docetaxel]], [[oxaliplatin]], [[capecitabine]], or [[irinotecan]].<ref name=Wagner17/>

[[File:Diagram showing secondary stomach cancer in the lungs CRUK 186.svg|thumb|right|Stomach cancer metastasized to the lungs]]

The [[TNM staging system]] is also used.<ref>{{cite web|url=http://www.cancer.org/docroot/CRI/content/CRI_2_4_3X_How_is_stomach_cancer_staged_40.asp|title=Detailed Guide: Stomach Cancer: How Is Stomach Cancer Staged?|publisher=American Cancer Society|url-status=live|archive-url=https://web.archive.org/web/20080325104115/http://www.cancer.org/docroot/CRI/content/CRI_2_4_3X_How_is_stomach_cancer_staged_40.asp|archive-date=25 March 2008}}</ref>

In a study of open-access endoscopy in [[Scotland]], patients were diagnosed 7% in stage I, 17% in stage II, and 28% in stage III.<ref>{{cite journal | vauthors = Paterson HM, McCole D, Auld CD | title = Impact of open-access endoscopy on detection of early oesophageal and gastric cancer 1994 - 2003: population-based study | journal = Endoscopy | volume = 38 | issue = 5 | pages = 503–507 | date = May 2006 | pmid = 16767587 | doi = 10.1055/s-2006-925124 | s2cid = 31841360 }}</ref> A Minnesota population was diagnosed 10% in stage I, 13% in stage II, and 18% in stage III.<ref>{{cite journal | vauthors = Crane SJ, Locke GR, Harmsen WS, Zinsmeister AR, Romero Y, Talley NJ | title = Survival trends in patients with gastric and esophageal adenocarcinomas: a population-based study | journal = Mayo Clinic Proceedings | volume = 83 | issue = 10 | pages = 1087–1094 | date = October 2008 | pmid = 18828967 | pmc = 2597541 | doi = 10.4065/83.10.1087 }}</ref> However, in a high-risk population in the [[Valdivia Province]] of southern [[Chile]], only 5% of patients were diagnosed in the first two stages and 10% in stage III.<ref name=Valdivia>{{cite journal | vauthors = Heise K, Bertran E, Andia ME, Ferreccio C | title = Incidence and survival of stomach cancer in a high-risk population of Chile | journal = World Journal of Gastroenterology | volume = 15 | issue = 15 | pages = 1854–1862 | date = April 2009 | pmid = 19370783 | pmc = 2670413 | doi = 10.3748/wjg.15.1854 | doi-access = free }}</ref>

==Prevention==
Getting rid of ''H. pylori'' in those who are infected decreases the risk of stomach cancer.<ref>{{cite journal | vauthors = Ford AC, Forman D, Hunt RH, Yuan Y, Moayyedi P | title = Helicobacter pylori eradication therapy to prevent gastric cancer in healthy asymptomatic infected individuals: systematic review and meta-analysis of randomised controlled trials | journal = BMJ | volume = 348 | article-number = g3174 | date = May 2014 | pmid = 24846275 | pmc = 4027797 | doi = 10.1136/bmj.g3174 }}</ref> A 2014 meta-analysis of observational studies found that a diet high in [[fruit]]s, [[Edible mushroom|mushrooms]], [[garlic]], [[soybean]]s, and [[green onion]]s was associated with a lower risk of stomach cancer in the Korean population.<ref name=Woo2014>{{cite journal | vauthors = Woo HD, Park S, Oh K, Kim HJ, Shin HR, Moon HK, Kim J | title = Diet and cancer risk in the Korean population: a meta- analysis | journal = Asian Pacific Journal of Cancer Prevention | volume = 15 | issue = 19 | pages = 8509–8519 | date = 2014 | pmid = 25339056 | doi = 10.7314/apjcp.2014.15.19.8509 | doi-access = free }}</ref> Low doses of [[vitamin]]s, especially from a [[healthy diet]], decrease the risk of stomach cancer.<ref>{{cite journal | vauthors = Kong P, Cai Q, Geng Q, Wang J, Lan Y, Zhan Y, Xu D | title = Vitamin intake reduce the risk of gastric cancer: meta-analysis and systematic review of randomized and observational studies | journal = PLOS ONE | volume = 9 | issue = 12 | article-number = e116060 | date = 2014 | pmid = 25549091 | pmc = 4280145 | doi = 10.1371/journal.pone.0116060 | doi-access = free | bibcode = 2014PLoSO...9k6060K }}</ref> A previous review of [[antioxidant]] supplementation did not find supporting evidence and possibly worse outcomes.<ref>{{cite journal | vauthors = Bjelakovic G, Nikolova D, Simonetti RG, Gluud C | title = Antioxidant supplements for preventing gastrointestinal cancers | journal = The Cochrane Database of Systematic Reviews | issue = 3 | article-number = CD004183 | date = July 2008 | pmid = 18677777 | doi = 10.1002/14651858.CD004183.pub3 | pmc = 12276870 }}</ref><ref>{{cite journal | vauthors = Bjelakovic G, Nikolova D, Gluud LL, Simonetti RG, Gluud C | title = Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases | journal = The Cochrane Database of Systematic Reviews | volume = 2012 | issue = 3 | article-number = CD007176 | date = March 2012 | pmid = 22419320 | pmc = 8407395 | doi = 10.1002/14651858.CD007176.pub2 | hdl-access = free | type = Submitted manuscript | hdl = 10138/136201 }}</ref> Modern technology is used to promote early diagnosis, e.g. based on serum markers.<ref>{{cite journal | vauthors = Aziz S, Rasheed F, Zahra R, König S | title = Gastric Cancer Pre-Stage Detection and Early Diagnosis of Gastritis Using Serum Protein Signatures | journal = Molecules | volume = 27 | issue = 9 | page = 2857 | date = April 2022 | pmid = 35566209 | pmc = 9099457 | doi = 10.3390/molecules27092857 | doi-access = free }}</ref>
Recent reviews have begun to explore the potential role of naturally derived compounds, such as diterpenes, in the prevention and treatment of gastric cancer.<ref>Ma C, Gao L, Song K, Gu B, Wang B, Pu W, Chen H. Exploring the therapeutic potential of diterpenes in gastric cancer: Mechanisms, efficacy, and clinical prospects. Biomolecules and Biomedicine. 2025;25(1):1–15.</ref>

==Management==
[[File:Infiltrative (poorly cohesive) gastric cancer.jpg|thumb|A [[gross anatomy]] specimen of a total [[gastrectomy]], [[splenectomy]] for infiltrative gastric cancer]]
[[File:Infiltrative gastric cancer showing thickened stomach wall.jpg|thumb|The same picture, close-up, total gastrectomy, infiltrative gastric cancer]]
Cancer of the stomach is difficult to cure unless it is found at an early stage (before it has begun to spread). Unfortunately, because early stomach cancer causes few symptoms, the disease is usually advanced when the diagnosis is made.<ref name="pmid23639645">{{cite journal | vauthors = Wadhwa R, Taketa T, Sudo K, Blum MA, Ajani JA | title = Modern oncological approaches to gastric adenocarcinoma | journal = Gastroenterology Clinics of North America | volume = 42 | issue = 2 | pages = 359–369 | date = June 2013 | pmid = 23639645 | doi = 10.1016/j.gtc.2013.01.011 }}</ref>

Treatment for stomach cancer may include surgery,<ref name="pmid23983442">{{cite journal | vauthors = Chen K, Xu XW, Zhang RC, Pan Y, Wu D, Mou YP | title = Systematic review and meta-analysis of laparoscopy-assisted and open total gastrectomy for gastric cancer | journal = World Journal of Gastroenterology | volume = 19 | issue = 32 | pages = 5365–5376 | date = August 2013 | pmid = 23983442 | pmc = 3752573 | doi = 10.3748/wjg.v19.i32.5365 | doi-access = free }}</ref> [[chemotherapy]],<ref name=Wagner17 /> or [[radiation therapy]].<ref name="pmid23622077">{{cite journal | vauthors = Pretz JL, Wo JY, Mamon HJ, Kachnic LA, Hong TS | title = Chemoradiation therapy: localized esophageal, gastric, and pancreatic cancer | journal = Surgical Oncology Clinics of North America | volume = 22 | issue = 3 | pages = 511–524 | date = July 2013 | pmid = 23622077 | doi = 10.1016/j.soc.2013.02.005 }}</ref> New treatment approaches such as [[immunotherapy]] or [[gene therapy]] and improved ways of using current methods are being studied in clinical trials.<ref name="pmid21556317">{{cite journal | vauthors = Meza-Junco J, Au HJ, Sawyer MB | title = Critical appraisal of trastuzumab in treatment of advanced stomach cancer | journal = Cancer Management and Research | volume = 3 | pages = 57–64 | date = March 2011 | pmid = 21556317 | pmc = 3085240 | doi = 10.2147/CMAR.S12698 | doi-access = free }}</ref>

===Surgery===
[[File:Diagam showing the anatomy before Roux-en-y surgery for stomach cancer CRUK 002.svg|thumb|right|Anatomy before Roux-en-y surgery to resect stomach cancer]]
Surgery remains the only curative therapy for stomach cancer.<ref name="WJG14"/> A 2016 [[Cochrane review]] found low-quality evidence of no difference in short-term mortality between laparoscopic and open gastrectomy (removal of stomach), and that benefits or harms of laparoscopic gastrectomy cannot be ruled out.<ref>{{cite journal | vauthors = Best LM, Mughal M, Gurusamy KS | title = Laparoscopic versus open gastrectomy for gastric cancer | journal = The Cochrane Database of Systematic Reviews | volume = 2016 | issue = 3 | article-number = CD011389 | date = March 2016 | pmid = 27030300 | pmc = 6769173 | doi = 10.1002/14651858.CD011389.pub2 }}</ref> Post-operatively, up to 70% of people undergoing total gastrectomy develop complications such as dumping syndrome and reflux esophagitis.<ref name=":0">{{cite journal | title = Pouch Versus No Pouch Following Total gastrectomy: Meta-analysis of Randomized and Non-randomized Studies | journal = Annals of Surgery | volume = 269 | issue = 6 | pages = 1041–1053 | date = December 2018 | pmid = 30571657 | doi = 10.1097/sla.0000000000003082 | s2cid = 58584460 | vauthors = Syn NL, Wee I, Shabbir A, Kim G, So JB }}</ref> 

Construction of a "pouch", which serves as a "stomach substitute", reduced the incidence of dumping syndrome and reflux esophagitis by 73% and 63% respectively, and led to improvements in quality-of-life, nutritional outcomes, and body mass index.<ref name=":0" /> Proximal gastrectomy can be considered a viable alternative for upper third early gastric cancer.<ref name="Narayan2024">{{cite journal |last1=Narayan |first1=Raja |last2=Kim |first2=Jane |last3=Park |first3=Do Joong |title=Robotic-assisted proximal gastrectomy with a laparoscopic-assisted double-tract reconstruction for proximal early gastric cancer |journal=J Med Insight |year=2024 |volume=2024 |issue=427 |doi=10.24296/jomi/427}}</ref> Of the different surgical techniques, [[endoscopic mucosal resection]]  is a treatment for early gastric cancer in which the tumor within the [[mucosa]] is removed using an electrical wire loop through the endoscope, providing a much smaller operation than removing the stomach.<ref name = "deyhle1974">{{cite journal |last1=Deyhle|first1=P. |last2=Sulser |first2=H. |last3=Säuberli |first3=H. |title=Endoscopic snare ectomy of an early gastric cancer - a therapeutical method? |journal=Endoscopy |year=1974 |volume=6 |issue=3 |pages=19-198 |doi=10.1055/s-0028-1098622}}</ref><ref name = WJG14/> Endoscopic submucosal dissection is a similar technique used to resect a large area of mucosa in one piece.<ref name = WJG14/> If the pathology examination of the resected specimen shows incomplete resection or deep invasion by tumor, the patient would need a formal stomach resection.<ref name = WJG14/> Uncut Roux-en-Y reconstruction after distal gastrectomy shows similar rates of major complications and anastomotic leakage compared with Billroth II and standard Roux-en-Y reconstruction. It may reduce the risk of bile reflux compared with Billroth II but increase it compared with Roux-en-Y.<ref>Cai H, Li Y, Wu X, et al. (June 2024). "Uncut Roux-en-Y reconstruction versus Billroth II and Roux-en-Y reconstruction after distal gastrectomy for gastric cancer". ''Cochrane Database of Systematic Reviews''. 2024(6): CD014943. doi:https://doi.org/10.1002/14651858.CD015014.pub2. PMID 38956467.</ref>

Those with metastatic disease at the time of presentation may receive palliative surgery, and while it remains controversial, due to the possibility of complications from the surgery itself and because it may delay chemotherapy, the data so far are mostly positive, with improved survival rates being seen in those treated with this approach.<ref name = WJG14/><ref>{{cite journal | vauthors = Sun J, Song Y, Wang Z, Chen X, Gao P, Xu Y, Zhou B, Xu H | title = Clinical significance of palliative gastrectomy on the survival of patients with incurable advanced gastric cancer: a systematic review and meta-analysis | journal = BMC Cancer | volume = 13 | issue = 1 | page = 577 | date = December 2013 | pmid = 24304886 | pmc = 4235220 | doi = 10.1186/1471-2407-13-577 | url = http://www.biomedcentral.com/content/pdf/1471-2407-13-577.pdf | url-status = live | archive-url = https://web.archive.org/web/20140407074334/http://www.biomedcentral.com/content/pdf/1471-2407-13-577.pdf | archive-date = 7 April 2014 | doi-access = free }}</ref>

===Chemotherapy===

Combination chemotherapy has been shown to improve overall survival compared with best supportive care in advanced gastric cancer, although the benefit remains modest and treatment is associated with increased toxicity.<ref>Nishizaki M, Syn NL, Wang L, Yoshikawa T, Lu Z, Gao TS, et al. (May 2021). "Chemotherapy versus best supportive care for advanced gastric cancer". ''The Cochrane Database of Systematic Reviews''. 2021 (5): CD012188. [https://doi.org/10.1002/14651858.CD012188.pub2 doi:10.1002/14651858.CD012188.pub2]</ref> The use of chemotherapy to treat stomach cancer has no firmly established [[standard of care]].<ref name=Wagner17 /> Unfortunately, stomach cancer has not been particularly sensitive to these drugs, and chemotherapy, if used, has usually served to palliatively reduce the size of the tumor, relieve symptoms of the disease, and increase survival time.<ref name=Wagner17 /> Some drugs used in stomach cancer treatment have included: fluorouracil or its analog [[capecitabine]], BCNU ([[carmustine]]), methyl-CCNU ([[semustine]]) and [[doxorubicin]] (Adriamycin), as well as [[mitomycin C]], and more recently [[cisplatin]] and [[taxotere]], often using drugs in various combinations.<ref name=Wagner17/> The relative benefits of these different drugs, alone and in combination, are unclear.<ref name=Wagner17 /><ref name="pmid17425475">{{cite journal | vauthors = Scartozzi M, Galizia E, Verdecchia L, Berardi R, Antognoli S, Chiorrini S, Cascinu S | title = Chemotherapy for advanced gastric cancer: across the years for a standard of care | journal = Expert Opinion on Pharmacotherapy | volume = 8 | issue = 6 | pages = 797–808 | date = April 2007 | pmid = 17425475 | doi = 10.1517/14656566.8.6.797 | s2cid = 24196381 }}</ref> Clinical researchers are exploring the benefits of giving chemotherapy before surgery to shrink the tumor, or as adjuvant therapy after surgery to destroy remaining cancer cells.<ref name = WJG14/>

===Targeted therapy===
Treatment with the [[HER2/neu|human epidermal growth factor receptor 2]] (HER2) inhibitor [[trastuzumab]] has been demonstrated to increase [[Overall survival rate|overall survival]] in inoperable locally advanced or metastatic gastric carcinoma over-expressing the ''[[HER2/neu]]'' gene.<ref name="WJG14" /> In particular, ''[[HER2/neu|HER2]]'' is overexpressed in 13–22% of patients with gastric cancer.<ref name="pmid21556317" /><ref name=Fusco13>{{cite journal | vauthors = Fusco N, Rocco EG, Del Conte C, Pellegrini C, Bulfamante G, Di Nuovo F, Romagnoli S, Bosari S | title = HER2 in gastric cancer: a digital image analysis in pre-neoplastic, primary and metastatic lesions | journal = Modern Pathology | volume = 26 | issue = 6 | pages = 816–824 | date = June 2013 | pmid = 23348899 | doi = 10.1038/modpathol.2012.228 | doi-access = free }}</ref> Of note, ''HER2'' overexpression in gastric neoplasia is heterogeneous and comprises a minority of tumor cells (less than 10% of gastric cancers overexpress ''HER2'' in more than 5% of tumor cells). Hence, this heterogeneous expression should be taken into account for ''HER2'' testing, particularly in small samples such as biopsies, requiring the evaluation of more than one bioptic sample.<ref name=Fusco13 />

A recent clinical study reported promising results for a combination therapy using [[nivolumab]] and [[catequentinib]] (anlotinib) in the treatment of advanced gastric adenocarcinoma (GAC) and esophageal squamous cell carcinoma (ESCC), that improve the immune response against cancer while simultaneously slowing tumor progression.<ref>{{Cite journal |last1=Wu |first1=Jing |last2=Zhang |first2=Shilong |last3=Yu |first3=Shan |last4=An |first4=Guo |last5=Wang |first5=Yi |last6=Yu |first6=Yiyi |last7=Liang |first7=Li |last8=Wang |first8=Yan |last9=Xu |first9=Xiaojing |last10=Xiong |first10=YanShi |last11=Shao |first11=Di |last12=Shi |first12=Zhun |last13=Li |first13=Nannan |last14=Wang |first14=Jingyuan |last15=Jin |first15=Dawei |date=2024-10-15 |title=Nivolumab plus anlotinib hydrochloride in advanced gastric adenocarcinoma and esophageal squamous cell carcinoma: the phase II OASIS trial |journal=Nature Communications |language=en |volume=15 |issue=1 |page=8876 |doi=10.1038/s41467-024-53109-4 |pmid=39406730 |issn=2041-1723|pmc=11480398 |bibcode=2024NatCo..15.8876W }}</ref> The research, conducted by Zhongshan Hospital, Fudan University, and BGI Genomics, was published in ''Nature Communications'' in October 2024. The study evaluated the efficacy of combining Nivolumab, an immunotherapy that enhances the immune system's ability to attack cancer cells, with anlotinib hydrochloride, a drug that inhibits tumor angiogenesis by blocking signals essential for the growth of new blood vessels.<ref>{{Cite web |title=New Combined Therapy Shows Promise for Advanced Stomach Cancer Treatment {{!}} Nature Communication |url=https://www.bgi.com/global/news/new-combined-therapy-for-advanced-stomach-cancer |access-date=2024-10-21 |website=www.bgi.com}}</ref>

===Radiation===

[[Radiation therapy]] (also called radiotherapy) may be used to treat stomach cancer, often as an adjuvant to chemotherapy and/or surgery.<ref name = WJG14/>

===Lymphoma===
[[MALT lymphoma]]s are often completely resolved after the underlying ''H. pylori'' infection is treated.<ref name=St2010/> This results in remission in about 80% of cases.<ref name=St2010/>

==Prognosis==
The prognosis of stomach cancer is generally poor, because the tumor has often metastasized by the time of discovery, and most people with the condition are elderly (median age is between 70 and 75 years) at presentation.<ref name=MSR>{{EMedicine|article|278744|Gastric Cancer}}</ref> The average life expectancy after being diagnosed is around 24 months, and the five-year survival rate for stomach cancer is less than 10%.<ref name = WJG14/>

Almost 300 genes are related to outcomes in stomach cancer, with both unfavorable genes where high expression is related to poor survival and favorable genes where high expression is associated with longer survival times.<ref name="atlas">{{cite web|title=The stomach cancer proteome – The Human Protein Atlas|url=https://www.proteinatlas.org/humanpathology/stomach+cancer|website=www.proteinatlas.org|access-date=21 September 2017|archive-date=21 September 2017|archive-url=https://web.archive.org/web/20170921144755/https://www.proteinatlas.org/humanpathology/stomach+cancer}}</ref><ref>{{cite journal | vauthors = Uhlen M, Zhang C, Lee S, Sjöstedt E, Fagerberg L, Bidkhori G, Benfeitas R, Arif M, Liu Z, Edfors F, Sanli K, von Feilitzen K, Oksvold P, Lundberg E, Hober S, Nilsson P, Mattsson J, Schwenk JM, Brunnström H, Glimelius B, Sjöblom T, Edqvist PH, Djureinovic D, Micke P, Lindskog C, Mardinoglu A, Ponten F | title = A pathology atlas of the human cancer transcriptome | journal = Science | volume = 357 | issue = 6352 | article-number = eaan2507 | date = August 2017 | pmid = 28818916 | doi = 10.1126/science.aan2507 | doi-access = free }}</ref> Examples of poor prognosis genes include [[ITGAV]], [[DUSP1]] and [[P2RX7]].<ref>{{cite journal | vauthors = Calik I, Calik M, Sarikaya B, Ozercan IH, Arslan R, Artas G, Dagli AF | title = P2X7 receptor as an independent prognostic indicator in gastric cancer | journal = Bosnian Journal of Basic Medical Sciences | volume = 20 | issue = 2 | pages = 188–196 | date = May 2020 | pmid = 32070268 | pmc = 7202194 | doi = 10.17305/bjbms.2020.4620 }}</ref>

==Epidemiology==
[[File:Stomach cancer world map-Deaths per million persons-WHO2012.svg|thumb|upright=1.25|Stomach cancer deaths per million persons in 2012
{{Div col|small=yes|colwidth=10em}}{{legend|#ffff20|0–11}}{{legend|#ffe820|12–16}}{{legend|#ffd820|17–24}}{{legend|#ffc020|25–33}}{{legend|#ffa020|34–51}}{{legend|#ff9a20|52–76}}{{legend|#f08015|77–102}}{{legend|#e06815|103–128}}{{legend|#d85010|129–175}}{{legend|#d02010|176–400}}{{div col end}}]]
In 2018, stomach cancer was the fifth most frequently diagnosed cancer worldwide, representing 5.7% of all cancer cases, and the third leading cause of death from cancers, being responsible for 8.2% of all cancer deaths.<ref name=":1">{{cite book |title=WHO report on cancer: setting priorities, investing wisely and providing care for all. |publisher=World Health Organization (WHO) |year=2020 |isbn=978-92-4-000129-9 |at=p. 26 |language=English}}</ref> Among men, 683,754 cases were diagnosed, accounting for 7.2% of all cancer cases, and among women, stomach cancer was diagnosed in 349,947 cases, accounting for 4.1% of all cancer cases.<ref name=":1" />

In 2012, stomach cancer was the fifth most-common cancer with 952,000 cases diagnosed.<ref name="WCR2014Epi" /> It is more common both in men and in developing countries.<ref name="Parkin">{{cite journal | vauthors = Parkin DM, Bray F, Ferlay J, Pisani P | title = Global cancer statistics, 2002 | journal = CA: A Cancer Journal for Clinicians| volume = 55 | issue = 2 | pages = 74–108 | year = 2005 | pmid = 15761078 | doi = 10.3322/canjclin.55.2.74 | s2cid = 13746942 | doi-access = free }}</ref><ref name="WHO-QA15">{{cite web |url=https://www.who.int/features/qa/15/en/index.html |title=Are the number of cancer cases increasing or decreasing in the world? |date=1 April 2008 |work=WHO Online Q&A |publisher=WHO |access-date=11 May 2009 |archive-url=https://web.archive.org/web/20090514012915/http://www.who.int/features/qa/15/en/index.html |archive-date=14 May 2009 }}</ref> In 2012, it represented 8.5% of cancer cases in men, making it the fourth most-common cancer in men.<ref>{{cite book |title = {{harvnb|World Cancer Report 2014}} |date = 2014 }}</ref> Also in 2012, the number of deaths was 700,000, having decreased slightly from 774,000 in 1990, making it the third-leading cause of cancer-related death (after [[lung cancer]] and [[liver cancer]]).<ref name="Loz2012">{{cite journal | vauthors = Lozano R, Naghavi M, Foreman K, Lim S, Shibuya K, Aboyans V, etal | title = Global and regional mortality from 235 causes of death for 20 age groups in 1990 and 2010: a systematic analysis for the Global Burden of Disease Study 2010 | journal = Lancet | volume = 380 | issue = 9859 | pages = 2095–2128 | date = December 2012 | pmid = 23245604 | doi = 10.1016/S0140-6736(12)61728-0 | pmc = 10790329 | hdl-access = free | s2cid = 1541253 | hdl = 10536/DRO/DU:30050819 | url = https://repozitorij.upr.si/Dokument.php?id=7123&dn= }}</ref><ref>{{cite web|title=PRESS RELEASE N° 224 Global battle against cancer won't be won with treatment alone: Effective prevention measures urgently needed to prevent cancer crisis|url=http://www.iarc.fr/en/media-centre/pr/2014/pdfs/pr224_E.pdf|work=World Health Organization|access-date=14 March 2014 |date=3 February 2014 |url-status=live |archive-url=https://web.archive.org/web/20140303133031/http://www.iarc.fr/en/media-centre/pr/2014/pdfs/pr224_E.pdf |archive-date=3 March 2014}}</ref>

Less than 5% of stomach cancers occur in people under 40 years of age, with 81.1% of that 5% in the age-group of 30 to 39 and 18.9% in the age-group of 20 to 29.<ref>{{cite journal |vauthors=Mauad EC, Nogueira JL, Souza JM, Wohnrath DR, Oliveira AT, Colli G, Colli AM |trans-title=Gastric Cancer in Young Adults |title=Câncer gástrico em adultos jovens |journal=Rev. Bras. Cancerol. |volume=46 |issue=3 |pages=299–304 |date=2000 |doi=10.32635/2176-9745.RBC.2000v46n3.2441 |s2cid=179189212 | url = http://www.inca.gov.br/rbc/n_46/v03/english/article6.html | url-status = live | archive-url = https://web.archive.org/web/20090703104120/http://www.inca.gov.br/rbc/n_46/v03/english/article6.html | archive-date = 3 July 2009 |doi-access=free }}</ref>

In 2014, stomach cancer resulted in 0.61% of deaths (13,303 cases) in the United States.<ref>{{cite web|url=http://www.worldlifeexpectancy.com/country-health-profile/united-states|title=Health profile: United States|publisher=Le Duc Media|access-date=31 January 2016|url-status=live|archive-url=https://web.archive.org/web/20160114181325/http://www.worldlifeexpectancy.com/country-health-profile/united-states|archive-date=14 January 2016}}</ref> In China, stomach cancer accounted for 3.56% of all deaths (324,439 cases).<ref>{{cite web|url=http://www.worldlifeexpectancy.com/country-health-profile/china|title=Health profile: China|publisher=Le Duc Media|access-date=31 January 2016|url-status=live|archive-url=https://web.archive.org/web/20160103182525/http://www.worldlifeexpectancy.com/country-health-profile/china|archive-date=3 January 2016}}</ref>{{unreliable source?|date=November 2021}} The highest rate of stomach cancer was in [[Mongolia]], at 28 cases per 100,000 people.<ref>{{cite web|url=http://www.worldlifeexpectancy.com/cause-of-death/stomach-cancer/by-country/|title=Stomach Cancer: Death Rate Per 100,000|publisher=Le Duc Media|access-date=13 March 2014|url-status=live|archive-url=https://web.archive.org/web/20140913035347/http://www.worldlifeexpectancy.com/cause-of-death/stomach-cancer/by-country/|archive-date=13 September 2014}}</ref>{{unreliable source?|date=November 2021}}

In the United Kingdom, stomach cancer is the 15th most-common cancer (around 7,100 people were diagnosed with stomach cancer in 2011), and it is the 10th most-common cause of cancer-related deaths (around 4,800 people died in 2012).<ref>{{cite web|title=Stomach cancer statistics|url=http://www.cancerresearchuk.org/cancer-info/cancerstats/types/stomach/|website=Cancer Research UK|access-date=28 October 2014|url-status=live|archive-url=https://web.archive.org/web/20141007170251/http://www.cancerresearchuk.org/cancer-info/cancerstats/types/stomach/|archive-date=7 October 2014}}</ref>

Incidence and mortality rates of gastric cancer vary greatly in Africa. The GLOBOCAN system is currently the most widely used method to compare these rates between countries, but African incidence and mortality rates are seen to differ among countries, possibly due to the lack of universal access to a registry system for all countries.<ref name="asom">{{cite journal | vauthors = Asombang AW, Rahman R, Ibdah JA | title = Gastric cancer in Africa: current management and outcomes | journal = World Journal of Gastroenterology | volume = 20 | issue = 14 | pages = 3875–3879 | date = April 2014 | pmid = 24833842 | pmc = 3983443 | doi = 10.3748/wjg.v20.i14.3875 | doi-access = free }}</ref> Variation as drastic as estimated rates from 0.3/100000 in Botswana to 20.3/100000 in Mali have been observed.<ref name="asom"/> In Uganda, the incidence of gastric cancer has increased from the 1960s measurement of 0.8/100000 to 5.6/100000.<ref name="asom"/> Gastric cancer, though present, is relatively low when compared to countries with high incidence like Japan and China. One suspected cause of the variation within Africa and between other countries is due to different strains of the ''H. pylori'' bacteria. The trend commonly seen is that ''H. pylori ''infection increases the risk for gastric cancer, but this is not the case in Africa, giving this phenomenon the name the "African enigma".<ref name="louw">{{cite journal | vauthors = Louw JA, Kidd MS, Kummer AF, Taylor K, Kotze U, Hanslo D | title = The relationship between ''Helicobacter pylori'' infection, the virulence genotypes of the infecting strain and gastric cancer in the African setting | journal = Helicobacter | volume = 6 | issue = 4 | pages = 268–273 | date = December 2001 | pmid = 11843958 | doi = 10.1046/j.1523-5378.2001.00044.x | s2cid = 25990463 }}</ref> Although this bacterial species is found in Africa, evidence has supported that different strains with mutations in the bacterial genotype may contribute to the difference in cancer development between African countries and others outside the continent.<ref name="louw"/> Increasing access to health care and treatment measures have been commonly associated with the rising incidence, though, particularly in Uganda.<ref name="asom"/>

==Other animals==

The stomach is a muscular organ of the [[gastrointestinal]] tract that holds food and begins the digestive process by secreting gastric juice. The most common cancers of the stomach are adenocarcinomas, but other histological types have been reported. Signs vary, but may include vomiting (especially if blood is present), weight loss, anemia, and lack of appetite. Bowel movements may be dark and tarry in nature. To determine whether cancer is present in the stomach, special X-rays and/or abdominal ultrasounds may be performed. [[Gastroscopy]], a test using an endoscope to examine the stomach, is a useful diagnostic tool that can also take samples of the suspected mass for histopathological analysis to confirm or rule out cancer. The most definitive method of cancer diagnosis is through open surgical biopsy.<ref name=MacEwan_2013>{{cite book | vauthors = Withrow SJ |chapter=22 Cancer of the Gastrointestinal tract § E: Gastric Cancer: Diagnostic Techniques and Work-Up |chapter-url=https://books.google.com/books?id=nYYlauGf0D4C&pg=PA402 | veditors = Vail DM |title=Withrow and MacEwen's Small Animal Clinical Oncology |publisher=Elsevier |edition=5th |date=2013 |isbn=978-0-323-24197-7 |pages=402–3 }}</ref>

== References ==
{{Reflist}}

== External links ==
{{Medical resources
|  DiseasesDB     = 12445
|  ICD10          = {{ICD10|C|16||c|15}}
|  ICD9           = {{ICD9|151}}
|  ICDO           =
|  OMIM           = 137215
|  MedlinePlus    = 000223
|  eMedicineSubj  = med
|  eMedicineTopic = 845
|  MeshID         = D013274
|  GeneReviewsName = Hereditary Diffuse Gastric Cancer
}}

{{Commons category}}
* {{cite web|work=[[National Cancer Institute]] |url=https://www.cancer.gov/types/stomach/hp/stomach-treatment-pdq#section/all |title=Gastric cancer treatment guidelines |date=14 October 2022 }}

{{Digestive system neoplasia}}

{{Authority control}}

{{DEFAULTSORT:Stomach Cancer}}
[[Category:Stomach cancer| ]]
[[Category:Abdomen]]
[[Category:Epstein–Barr virus–associated diseases]]
[[Category:Infectious causes of cancer]]
[[Category:Wikipedia medicine articles ready to translate]]