OncoFirm™ / Cancer Atlas 2026 / Gastric cancer
Cancer Atlas 2026 · Gastric cancer
Gastric (Stomach) Cancer Biomarkers and Early Detection in 2026: H. pylori, HER2 and Claudin 18.2
Gastric (stomach) cancer is the fifth most common cancer and the fifth leading cause of cancer death worldwide. Most cases trace back to one treatable infection, yet few countries screen for it. This article covers the burden, how stage shapes survival, who is screened as of 1 October 2026, and which biomarkers guide treatment.
At a glance
Global burden
About 980,000 new cases and 642,000 deaths in 2024; fifth for both (GLOBOCAN 2024).
United States, 2026
About 31,510 new cases and 10,740 deaths. 35% of cases are found at distant stage.
Screening
No US population screening. Endoscopy programs in South Korea and Japan. H. pylori screen-and-treat is under study.
Key biomarkers
HER2, PD-L1, MMR/MSI and claudin 18.2, all tested on tumor tissue to choose treatment.
OncoFirm™ status
No gastric cancer assay. CEA assay in development, research use only, not for screening.
On this page
Key numbers
Gastric cancer in three numbers
980,000new stomach cancer cases worldwide in 2024
78.1%5-year relative survival when found at localized stage (US)
8.1%5-year relative survival when found at distant stage (US)
Sources: IARC Global Cancer Observatory (GLOBOCAN 2024) and SEER Cancer Stat Facts, cases diagnosed 2016–2022.
Burden
How common is gastric cancer, and what causes it?
Gastric cancer starts in the lining of the stomach. GLOBOCAN 2024, the global estimate from the International Agency for Research on Cancer (IARC), counts 980,286 new cases and 641,554 deaths in 2024. That is roughly two deaths for every three new cases, a worse ratio than for colorectal cancer. Rates are about twice as high in men as in women. They are highest in Eastern Asia, followed by Eastern Europe and South America. This page is part of the OncoFirm™ Cancer Atlas 2026.
In the United States, an estimated 31,510 people will be diagnosed and 10,740 will die of stomach cancer in 2026. It makes up 1.5% of new cancer cases.
Doctors divide the disease by location. Cardia cancer arises at the top of the stomach, next to the esophagus, and is linked to excess body weight and acid reflux. Non-cardia cancer arises in the rest of the stomach. Helicobacter pylori (H. pylori), a bacterium that infects the stomach lining, accounts for about 90% of non-cardia cancers worldwide. Rates have fallen over the past century as this infection, smoking and salt-preserved food became less common.
The burden is still large. One modeling study projects 15.6 million gastric cancers over the lifetimes of people born in 2008–2017, with 76% of all cases attributable to H. pylori and 68% in Asia. Sub-Saharan Africa may see up to a six-fold rise from 2022 levels. See the global need for affordable diagnostics.
Why stage matters
Stage at diagnosis drives survival
Stomach cancer: 5-year relative survival and share of cases by stage, United States, 2016–2022. Source: SEER Cancer Stat Facts (accessed 1 October 2026).
The chart shows 5-year relative survival: the share of patients alive five years after diagnosis, compared with similar people without the cancer. The US SEER registries use three stages: localized (confined to the stomach), regional (spread to nearby lymph nodes or tissues) and distant (spread to other organs).
For cases diagnosed in 2016–2022, survival was 78.1% for localized, 39.0% for regional and 8.1% for distant disease (39.8% across all stages). Only 32% of cases were found while localized; 23% were regional, 35% distant and 9% unstaged. By comparison, 23% of colorectal cancers are distant at diagnosis.
In South Korea, 5-year survival rose from 49% in 2000 to 77% in 2013–2019 after national screening began. Survival gains can partly reflect earlier diagnosis itself, so they are not proof of fewer deaths. See why early detection matters.
Screening
Screening today: no US program, endoscopy in East Asia
As of 1 October 2026, the United States has no population screening for gastric cancer. An American Gastroenterological Association (AGA) expert review from December 2024 advises upper endoscopy, a camera exam of the stomach, for people at higher risk. These include first-generation immigrants from high-incidence regions, people with a parent, sibling or child who had gastric cancer, and people with hereditary gastrointestinal syndromes.
| Region | Approach | Status |
|---|---|---|
| United States | Endoscopy for higher-risk groups only | Expert review, 2024; no national program |
| South Korea | Every 2 years, ages 40 to 74, mostly endoscopy | National program since 1999 |
| Japan | X-ray or endoscopy | National program since 1983; 2018 guideline |
| European Union | H. pylori screen-and-treat where rates are high | To be considered (Council, 2022) |
In South Korea, a nested case-control study found 47% lower gastric cancer mortality among people screened by endoscopy. The GLOBOCAN 2024 paper cites a 41% fall in mortality 15 years after the program began. The two figures come from different study designs. Participation rose from 38.2% in 2009 to 70.8% in 2022.
Screen-and-treat means testing people for H. pylori and giving antibiotics to those infected. The Maastricht VI expert consensus calls the infection the most important cause of gastric adenocarcinoma and supports population test-and-treat, especially where infection is common. IARC published implementation guidance in 2025. The modeling study above estimates that up to 75% of expected cases could be prevented if screen-and-treat were fully effective.
Blood tests for risk. Pepsinogens are proteins made by the stomach lining. Low blood levels point to atrophy, a thinning of the lining that raises cancer risk. Japan’s ABC method combines pepsinogen with H. pylori antibodies to sort people into risk groups. Even so, Japan’s 2018 guideline does not recommend either test for population screening, citing insufficient evidence. The AGA review relies on endoscopy. The early detection evidence hub tracks guidance for other cancers.
Key limit. Pepsinogen and H. pylori blood tests flag risk. They do not detect cancer, and no protein tumor marker is recommended for gastric cancer screening.
Biomarkers
Established biomarkers by clinical role
A biomarker is a measurable sign of disease or of response to treatment (see cancer biomarkers explained). In advanced gastric cancer, every marker that selects treatment is measured on tumor tissue. NCCN 2026 guidance, as summarized in secondary reports, recommends testing HER2, PD-L1, MMR/MSI and claudin 18.2.
| Biomarker | Type | Used for | Not used for |
|---|---|---|---|
| HER2 (tissue) | Predictive | Trastuzumab-based therapy | Screening |
| PD-L1 (tissue) | Predictive | Adding a PD-1 inhibitor to chemotherapy | Screening |
| MMR/MSI (tissue) | Predictive | Recommended test in advanced disease | Screening |
| Claudin 18.2 (tissue) | Predictive | Zolbetuximab with chemotherapy | Screening |
| CEA, CA 19-9, CA 72-4 (blood) | Monitoring | Add-ons for following known disease | Screening or diagnosis |
| Pepsinogen, H. pylori antibodies (blood) | Risk | Flagging atrophy and infection | Diagnosing cancer |
HER2 is a growth-signal receptor on the cell surface. It is positive in about 15% of gastric cancers and up to 30% of cancers at the junction with the esophagus. Results differ between the first tumor and its metastases in nearly 20% of cases. HER2-positive disease is treated with trastuzumab plus chemotherapy, with pembrolizumab added.
PD-L1 is a protein that helps tumors avoid immune attack. In HER2-negative, PD-L1-positive disease, a PD-1 inhibitor is added to chemotherapy. MMR (mismatch repair) is the cell’s DNA proofreading system; when it fails, tumors show microsatellite instability (MSI).
Claudin 18.2 (CLDN18.2) is a cell-membrane protein. The FDA approved zolbetuximab on 18 October 2024, with chemotherapy, for HER2-negative advanced disease. A tumor counts as positive when at least 75% of its cells show moderate-to-strong membrane staining on an FDA-approved test. Median overall survival was 18.2 versus 15.5 months in the SPOTLIGHT trial and 14.4 versus 12.2 months in GLOW. A further target, FGFR2b, remains investigational: the survival benefit of bemarituzumab weakened with longer follow-up (hazard ratio 0.61, later 0.82).
Serum markers and antigens
Serum protein markers and tumor-associated antigens
Tumor-associated antigens are normal molecules that tumors make in unusual amounts or forms. Three are measured in blood in gastric cancer, and none finds early disease. In 12,349 adults without symptoms in Japan, CEA found 7.8% and CA 19-9 found 7.4% of gastrointestinal cancers.
- CA 19-9 is a sugar structure called sialyl-Lewis a. About 6% of Caucasian and 22% of non-Caucasian people cannot make it, so their result stays low even with cancer.
- CA 72-4 was raised in about 42.6% of gastric cancer patients in early series, with specificity above 95%. It is an add-on for monitoring, not a diagnostic test.
Research only. The Thomsen-Friedenreich (TF) antigen and related short sugar chains (Tn, sialyl-Tn) have been studied in stomach tissue since the 1990s. People also carry natural antibodies to TF, and their levels shift in gastric cancer. A 2020 review reports sensitivity and specificity of up to 80% for antibody-based markers, but the data come mostly from small, single-center studies by one research group, and levels vary with blood group. We found no multicenter validation.
Emerging
Emerging approaches in 2025 and 2026
Multi-cancer blood tests. In countries that do not screen, a multi-cancer early detection (MCED) test is the most likely way a blood test could reach gastric cancer. These tests read tumor DNA in blood, a form of liquid biopsy. In the PATHFINDER 2 study, about 70% of cancers detected were types with no recommended screening test; stomach-specific figures were not available to us. As of 1 October 2026, no MCED test is FDA approved. The NHS-Galleri randomized trial missed its primary endpoint. An FDA advisory panel backed the Galleri test on 23 September 2026; the decision is pending.
Blood-based risk sorting outside East Asia. A small US case-control study (32 cancers, 60 controls) combined the pepsinogen ratio with H. pylori antibody levels and reported 87.9% sensitivity and 50.8% specificity. That is too many false alarms for screening, but it supports more research. IARC’s 2025 report says risk sorting by infection and atrophy status warrants further study. In South Korea, the HELPER general-population trial, begun in 2014 with IARC, is ongoing.
We found no sources that met our standard on AI-assisted endoscopy or stomach-specific DNA blood tests, so this edition does not cover them. For the wider field, see emerging cancer diagnostic technologies and multi-biomarker analysis.
Open questions
Open research questions
- Who should be screened in low-incidence countries? US advice rests on expert review, not on a trial-based program.
- Does screen-and-treat work at population scale? Who to test, at what age, with which test, and the effect on antibiotic resistance are being studied.
- Can blood tests direct endoscopy? Japan's own guideline found the evidence insufficient for population use.
- Can any blood marker find early disease? CEA and CA 19-9 each found fewer than 1 in 10 gastrointestinal cancers in adults without symptoms.
- How should small biopsies be shared? HER2, PD-L1, MMR and claudin 18.2 now compete for the same tissue.
OncoFirm™ roadmap
Where OncoFirm™ fits, and where it does not
OncoFirm™ is developing a fluorescent lateral flow platform: a test strip read by a small instrument. The assays, reader and software are in development, have not been cleared or approved by the FDA or any other regulatory authority, are for research use only and are not for sale. OncoFirm™ has no gastric cancer assay and makes no screening claims.
No gastric cancer test
No serum marker selects treatment or screens for gastric cancer today. OncoFirm™ does not claim otherwise. See the evidence hub.
CEA assay in development
The CEA assay is designed for 1–100 ng/mL, with planned traceability to the WHO reference preparation for CEA (73/601). In gastric cancer, CEA is at most an add-on for monitoring.
TF antigen: concept-stage
OncoFirm™ assay concepts for the TF antigen are concept-stage research. Clinical validation is lacking.
Platform, not a product
The platform has a result-time target of 20 minutes or less (a development target). It is not for sale.
OncoFirm™ assays, reader and software are in development, have not been cleared or approved by the FDA or any other regulatory authority, are for research use only and are not for sale. Designed ranges and result times are development targets, not validated performance claims.
FAQ
Frequently asked questions
Is there a screening test for stomach cancer in the United States?
No. As of 1 October 2026 there is no population screening program for stomach cancer in the United States. Expert advice supports upper endoscopy for people at higher risk, such as those with a close relative who had gastric cancer. South Korea and Japan run national programs.
Does treating H. pylori prevent stomach cancer?
H. pylori infection is the main cause of non-cardia stomach cancer. Expert consensus supports testing for and treating the infection to prevent cancer, especially where infection is common. How best to run such programs is still being studied.
Can a blood test find stomach cancer early?
Not today. In a study of more than 12,000 adults without symptoms, CEA and CA 19-9 each found fewer than 1 in 10 gastrointestinal cancers. Pepsinogen and H. pylori blood tests flag risk, not cancer.
Which biomarkers guide stomach cancer treatment?
In advanced disease, doctors test tumor tissue for HER2, PD-L1, mismatch repair or microsatellite instability, and claudin 18.2. The results help choose between targeted drugs, immunotherapy and chemotherapy. None of these is a screening test.
Does OncoFirm™ have a stomach cancer test?
No. OncoFirm™ has no gastric cancer assay. Its CEA assay, reader and software are in development and for research use only. They are not cleared or approved by the FDA or any other regulatory authority and are not for sale.
Cancer Atlas 2026
More in the Atlas
Related OncoFirm™ guides
Sources
References
- Sung H, et al. Global cancer statistics 2024: GLOBOCAN estimates of incidence and mortality worldwide for 34 cancers in 186 countries. CA Cancer J Clin. Online 8 July 2026. acsjournals.onlinelibrary.wiley.com/doi/10.3322/caac.70090
- International Agency for Research on Cancer. Global Cancer Observatory: World fact sheet, GLOBOCAN 2024. gco.iarc.who.int/media/globocan/factsheets/populations/900-world-fact-sheet.pdf
- National Cancer Institute. SEER Cancer Stat Facts: Stomach Cancer. Accessed 1 October 2026. seer.cancer.gov/statfacts/html/stomach.html
- Park JY, et al. Modeling study of lifetime gastric cancer burden in people born 2008–2017. Nature Medicine. 2025;31(9):3020-3027. www.nature.com/articles/s41591-025-03793-6
- Shah SC, Wang AY, Wallace MB, Hwang JH. AGA Clinical Practice Update on screening and surveillance in high-risk US populations for gastric cancer: expert review. Gastroenterology. Online 23 December 2024. www.gastrojournal.org/article/S0016-5085%2824%2905663-4/fulltext
- IARC Working Group. Population-Based Helicobacter pylori Screen-and-Treat Strategies for Gastric Cancer Prevention: Guidance on Implementation. 2025. www.ncbi.nlm.nih.gov/books/NBK615785/
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- Council of the European Union. Council Recommendation of 9 December 2022 on cancer screening (2022/C 473/01). eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CELEX:32022H1213(01)
- Malfertheiner P, et al. Maastricht VI/Florence consensus report on Helicobacter pylori infection. Gut. 2022;71(9):1724. gut.bmj.com/content/71/9/1724
- In H, et al. Serum pepsinogen and H. pylori serology for gastric cancer risk in a US case-control study. Surgical Oncology Insight. 2024. www.sciencedirect.com/science/article/pii/S2950247024000951
- OncoDaily. Summary of NCCN 2026 updates for gastric and esophageal cancers. 28 March 2026. oncodaily.com/new-paper-alert/nccn-2026-updates-gastric-esophageal
- US Food and Drug Administration. FDA approves zolbetuximab-clzb with chemotherapy for gastric or gastroesophageal junction adenocarcinoma. 18 October 2024. www.fda.gov/drugs/resources-information-approved-drugs/fda-approves-zolbetuximab-clzb-chemotherapy-gastric-or-gastroesophageal-junction-adenocarcinoma
- The ASCO Post. Primary analysis of bemarituzumab plus chemotherapy in gastric or gastroesophageal junction cancer. 10 December 2025. ascopost.com/issues/december-10-2025/primary-analysis-shows-survival-benefit-with-bemarituzumab-plus-chemotherapy-in-gastric-or-gastroesophageal-junction-cancer/
- Sekiguchi M, Matsuda T. Serum CEA and CA 19-9 for cancer screening in 12,349 asymptomatic adults. Scientific Reports. 2020. www.nature.com/articles/s41598-020-75319-8
- Lee, Teng, Shelat. Review of carbohydrate antigen 19-9. World J Gastrointest Surg. 2020;12:468-490. www.wjgnet.com/1948-9366/full/v12/i12/468.htm
- Mariampillai AI, et al. Review of the tumor marker CA 72-4. Anticancer Research. 2017;37(7):3649. ar.iiarjournals.org/content/37/7/3649
- Kurtenkov O. Review of antibodies to the Thomsen-Friedenreich antigen in cancer. BioMed Research International. 2020;2020:9747040. www.hindawi.com/journals/bmri/2020/9747040/
- Sotozono M, et al. Thomsen-Friedenreich-related antigens in gastric intestinal metaplasia and cancer. J Histochem Cytochem. 1994. journals.sagepub.com/doi/10.1177/42.12.7527063
- Oregon Health & Science University. PATHFINDER 2 findings on multi-cancer early detection blood testing. 22 September 2026. news.ohsu.edu/2026/09/22/pathfinder-2-findings-advance-multi-cancer-early-detection-blood-testing
- The ASCO Post. Report on the NHS-Galleri randomized trial results. June 2026. ascopost.com/news/june-2026/annual-galleri-screening-reduced-stage-iv-cancer-diagnoses-but-missed-primary-endpoint-in-first-randomized-mced-trial/
- Targeted Oncology. FDA advisory panel vote on the Galleri test, 23 September 2026. www.targetedonc.com/view/fda-panel-galleri-multi-cancer-early-detection-test
About this article. Compiled from registry data, guidelines, trial reports and news releases available on 1 October 2026; several guideline and trial details come from secondary summaries and should be checked against the primary documents. Part of the OncoFirm™ Cancer Atlas 2026, written by the OncoFirm™ Scientific Team from the sources linked above and reflecting public information as of 1 October 2026. It is for education and is not medical advice. OncoFirm™ has no affiliation with the companies or tests named. OncoFirm™ assays are in development, have not been cleared or approved by the FDA and are not available for sale.
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