Stomach Cancer 101

Swedish Cancer Institute

Stomach cancer—also called gastric cancer—is a major global health concern, causing nearly one million new cases each year. This comprehensive guide explores stomach cancer types, causes, symptoms, prevention strategies, early detection methods, and the latest treatment advances to help patients and caregivers better understand this complex disease.

Introduction

Stomach cancer, also known as gastric cancer, is a major health challenge worldwide, with up to 1 million cases causing more than 650,000 deaths each year. The sections below provide an overview of stomach cancer, including types, incidence trends, and disparities, symptoms, prevention strategies, treatment options, and patient perspectives.

Stomach Cancer Overview: What Is Stomach Cancer?

Gastric cancer, commonly referred to as stomach cancer, develops from the inner lining of the stomach and is the fifth most frequently diagnosed cancer globally. In 2025, approximately 1 million new cases are expected worldwide, with the highest incidence in East Asia, Eastern Europe, and Latin America. Despite advances in treatment, the disease often remains lethal, especially when diagnosed at later stages.

What Causes Stomach Cancer?

Stomach cancer arises from a complex interplay of genetic, environmental, and lifestyle factors that change the cells lining the stomach, sometimes leading to tumor formation. Many of these risk factors can be modified, while others, such as age or inherited conditions, are unmodifiable.

These factors vary in how much they contribute to individual risk, but addressing modifiable risks such as diet, infection, and lifestyle habits may help lower the likelihood of developing stomach cancer.

Helicobacter pylori infection: Chronic infection with this bacterium damages the stomach lining and is the strongest known risk factor.
Diet high in salt, smoked, and processed foods: Consuming salted, pickled vegetables and smoked meats increases carcinogenic exposure to the gastric mucosa.
Tobacco smoking: Smoking doubles the risk by exposing the stomach to cancer-promoting chemicals.
Heavy alcohol consumption: Increased alcohol intake fosters chronic inflammation and cell injury in the stomach.
Obesity: Excess body weight, especially abdominal fat, creates a pro-inflammatory state, encouraging cancer development.
Chronic gastritis and stomach conditions: Long-term inflammation, ulcers, or atrophic changes heighten cancer risk.
Inherited cancer syndromes: Gene mutations such as those found in hereditary diffuse gastric cancer (HDGC), Lynch syndrome, and familial adenomatous polyposis dramatically increase lifetime risk. 1-3% of stomach cancers are HDGC and is caused by a mutation in the CDH1 gene.
Family history of gastric cancer: Having first-degree relatives with stomach cancer raises risk, even without a known genetic syndrome.
Previous stomach surgery: Reconstructive or ulcer surgeries can alter normal cell growth in the stomach, increasing risk.
Gastric polyps: Certain benign growths may progress to cancer over time.
Older age: Stomach cancer rates rise after age 50 due to cumulative damage and genetic mutations.
Male gender: Men are more likely than women to develop stomach cancer.
Epstein-Barr virus infection: This virus has been linked to gastric carcinoma in select individuals.
Environmental and occupational exposures: Contact with radiation, asbestos, some chemicals, or ionizing radiation can increase risk.
Type A blood: People with type A blood may have a slightly increased risk due to genetic factors.

Types of Stomach Cancer

The most common type is adenocarcinoma, which originates from glandular tissue. Other less common types include:

Squamous cell carcinoma
Lymphoma (arising from immune cells)
Gastrointestinal stromal tumors (GIST)
Carcinoid tumors

Gastric adenocarcinomas are further classified into intestinal and diffuse subtypes based on microscopic features.

Stages of Stomach Cancer

Stomach cancer is staged from 0 (earliest) to IV (most advanced) to guide treatment. Staging is determined by:

Tumor size and local invasion
Involvement of lymph nodes
Distant metastasis

According to the Surveillance, Epidemiology, and End Results (SEER) Statistics in the United States, the staging breaks down as follows:

Stage and the 5-Year Relative Survival Rate:

Localized (confined to the primary site) - 76.5%
Regional (spread to lymph nodes) - 37.2%
Distant (metastasized) - 7.5%

Early-stage diagnosis offers the best chance for a cure, but most cases are found at later stages due to subtle symptoms.

Stomach Cancer Signs and Symptoms

Early gastric cancer is often asymptomatic or vague, leading to delayed diagnosis. Common symptoms, when present, include:

Persistent indigestion or heartburn
Feeling bloated after meals
Mild nausea or loss of appetite
Early satiety (feeling full after small meals)
Unintentional weight loss
Abdominal pain (above the navel)
Difficulty swallowing
Vomiting (sometimes with blood)
Black or bloody stools
Constant fatigue

These symptoms are non-specific and often resemble common digestive issues.

Stomach Cancer Prevention and Early Detection

Stomach cancer prevention strategies focus on reducing modifiable risk factors, including eradicating H. pylori infection, adopting a diet rich in fruits and vegetables, low in salt, and low in processed meats, avoiding tobacco and limiting alcohol, and maintaining a healthy weight and regular physical activity.

Early detection of stomach (gastric) cancer focuses on identifying high-risk individuals and diagnosing cancer at its earliest, most treatable stages. Screening programs for gastric cancer are most effective in high-risk populations (such as certain East Asian countries). Still, ongoing research is also looking for practical, non-invasive methods appropriate for general use.

Patients with high-risk precancerous lesions, such as Barrett's esophagus, need to receive more frequent follow-up and often frequent endoscopy.

Methods for Early Detection

Serum Biomarkers: Blood tests measuring substances such as serum pepsinogen, gastrin-17, carcinoembryonic antigen (CEA), and antibodies to H. pylori can suggest atrophic gastritis, a precancerous change. While these markers help stratify risk groups, they lack enough accuracy to serve as a stand-alone screening test for early cancer.
Molecular Biomarkers: Recent advances include the use of circulating microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) in blood samples, also known as "liquid biopsies." Specific miRNA panels, like the Destinex assay, have shown high sensitivity and specificity for detecting early-stage gastric cancer in research settings. These non-invasive tests are promising, but most are not yet widely available or approved for routine screening.
Imaging and Endoscopy: In countries such as Japan and South Korea, gastric cancer screening programs use upper endoscopy (and sometimes barium X-rays) for adults starting at age 40–50. Endoscopy remains the gold standard for early detection since it allows direct visualization and biopsy of abnormal areas. Technology advances, such as magnifying and digital endoscopy, are further improving accuracy.

Currently, endoscopy is the most reliable approach for early detection in high-risk individuals, while non-invasive serum or molecular biomarker tests remain an active area of research aimed at broader screening in the future.

Stomach Cancer Treatment Options

Stomach cancer treatment options have advanced significantly in recent years, emphasizing personalized care and improved quality of life. Treatment options now include immunotherapy, targeted therapies, antibody-drug conjugates (ADCs), and innovative surgical techniques.

Immunotherapy: Immunotherapy has become transformative for stomach cancer care, offering substantial survival benefits when combined with chemotherapy. For example, Nivolumab plus chemotherapy extends survival markedly in selected groups, and pembrolizumab (often with trastuzumab) is effective in HER2-positive tumors. Based on the MATTERHORN study, perioperative chemotherapy and immunotherapy (FLOT +durvalumab) is now the preferred standard of care option for early-stage gastric cancer.
Molecular Targeted Therapies: Precision oncology developments have enriched options for specific stomach cancer subtypes. Targets such as HER2, CLDN18.2, FGFR2b, c-Met, and EGFR are part of a new wave of individualized treatment strategies.
Function-Preserving Surgery: In early-stage disease, new surgical techniques like laparoscopic sentinel lymph node navigation surgery prioritize preserving gastric function. These methods yield comparable tumor control and disease-free survival to traditional gastrectomy. Minimally invasive approaches, including robotic assistance and combined endoscopic-laparoscopic procedures, are under active investigation for their effectiveness and safety.
Antibody-Drug Conjugates (ADCs): ADCs combine targeted therapy with cytotoxic drugs to deliver treatment directly to cancer cells. ADC is now the standard of care second-line therapy for HER2-amplified metastatic gastric cancer.

Today’s stomach cancer treatments reflect a paradigm shift, emphasizing targeted, less invasive, and function-preserving care. Combination regimens, along with new immunotherapies and surgical options, offer new hope for improved survival and quality of life across all disease stages. The choice and combination of treatments are tailored by multidisciplinary teams based on the latest research and clinical trial data. Precision medicine has also gained significant traction in stomach cancer treatment. Oncologists are now using next-generation sequencing and immunohistochemistry data to tailor treatments for individual patients.

Ask An Expert

Have questions about stomach cancer? Submit them to connect with gastric cancer specialists for evidence-based answers tailored to individual risk, values, and goals of care.

Share Your Story

Lived experiences help raise awareness and support others navigating screening, diagnosis, treatment decisions, and survivorship in prostate cancer communities. Interested in sharing your journey? Share your story here.

More Resources

Stomach Cancer Advocacy Organizations

These organizations provide patient support, fund research, raise awareness, and advocate for better treatment options for stomach cancer patients and their families.

United States:

Debbie's Dream Foundation (https://debbiesdream.org/)
No Stomach For Cancer (https://nostomachforcancer.org/)
Hope For Stomach Cancer (Stomach Cancer Awareness Network) (https://stocan.org/)
Gastric Cancer Foundation (https://gastriccancer.org/)
DeGregorio Foundation (https://degregorio.org/)

International:

GI Cancers Alliance (https://www.gicancersalliance.org/)
Cancer Research UK (http://www.cancerresearchuk.org/about-cancer/stomach-cancer)
Australian Cancer Research Foundation (https://www.acrf.com.au/)
GI Cancer Institute – Australasian Gastro-Intestinal Trials Group (https://gicancer.org.au/)
Gut Cancer Foundation - New Zealand (http://www.gutcancer.org.nz/)
Canadian Cancer Survivor Network (http://survivornet.ca/)

Learn More About Stomach Cancer Clinical Trials

Major Clinical Trial Databases:

National Cancer Institute (NCI) Clinical Trials (https://www.cancer.gov/research/participate/clinical-trials/disease/stomach-cancer/treatment)

ClinicalTrials.gov (https://clinicaltrials.gov/)
No Stomach For Cancer - Clinical Trials Resources (https://nostomachforcancer.org/after-diagnosis/treatments-clinical-trials/stomach-cancer-clinical-trials/)

Major Cancer Centers:

Memorial Sloan Kettering Cancer Center (https://www.mskcc.org/cancer-care/types/stomach-gastric/clinical-trials)
Mayo Clinic Research (https://www.mayo.edu/research/clinical-trials/diseases-conditions/stomach-cancer)
Mass General (Massachusetts General Hospital) (https://www.massgeneral.org/cancer-center/clinical-trials-and-research/search-clinical-trials?cancerCondition=Gastric+(Stomach)+Cancer)
Columbia University (https://cancer.columbia.edu/clinical-trials)
UCSF Clinical Trials (https://clinicaltrials.ucsf.edu/stomach-cancer)
UC San Diego Clinical Trials (https://clinicaltrials.ucsd.edu/stomach-cancer)
UCLA Clinical Trials (https://ucla.clinicaltrials.researcherprofiles.org/stomach-cancer)

Pharmaceutical Companies:

MSD (Merck) Clinical Trials (https://www.msdclinicaltrials.com/oncology/gastric/)
Merck Oncology Clinical Trials (https://merckoncologyclinicaltrials.com/en-us/patient/gastric)

References

Mazurek, M., Szewc, M., Sitarz, M. Z., Dudzińska, E., & Sitarz, R. (2024). Gastric Cancer: An Up-to-Date Review with New Insights into Early-Onset Gastric Cancer. Cancers, 16(18), 3163. https://doi.org/10.3390/cancers16183163

National Cancer Institute. (2025, May 8). Stomach cancer causes and risk factors. https://www.cancer.gov/types/stomach/causes-risk-factors

Menon G, El-Nakeep S, Babiker HM. Gastric Cancer. [Updated 2024 Oct 28]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK459142/

Lopes, C., & Pereira, C. (2025). Advances towards gastric cancer screening: Novel devices and biomarkers. Best practice & research. Clinical gastroenterology, 75, 102009. https://doi.org/10.1016/j.bpg.2025.102009

Wei, J., & Bu, Z. (2024). Advances in gastric cancer treatment in 2024: Key breakthroughs and emerging trends. Chinese journal of cancer research = Chung-kuo yen cheng yen chiu, 36(6), 592–595. https://doi.org/10.21147/j.issn.1000-9604.2024.06.02

Medical Reviewer

Dr. Ronan Hsieh is a gastroenterologist currently affiliated with the Swedish Cancer Institute in Seattle, Washington. He is also a Clinical Assistant Professor of Medicine at Washington State University and a committee member at the NCI Task Force. With a focus on gastrointestinal (GI) cancers, he specializes in the treatment of conditions such as colorectal cancer and other gastrointestinal malignancies. Dr. Hsieh has a strong interest in drug development, clinical trials, and clinical research, and he actively participates in advancing the field of oncology.