The short answer
Long-term infection with H. pylori bacteria is a major risk factor for stomach cancer. Smoking, certain diets high in salted or smoked foods, older age, and family history also raise risk. Treating H. pylori can lower risk.
Long-term H. pylori bacterial infection is a major risk factor.
Smoking raises the risk of stomach cancer.
Diets high in salted, smoked, or pickled foods are linked to higher risk.
Older age, being male, and family history raise risk.
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The full explanation.
The simple version
A risk factor is anything that raises the chance of a disease. It does not mean you will get that disease. For stomach cancer, long-term infection with a common bacterium called H. pylori is the biggest known risk factor. Unlike most risk factors, this one can be tested for and treated.
H. pylori infection
H. pylori lives in the stomach lining of a large share of adults worldwide. Most people who carry it never have a problem. But in some people, it causes years of low-grade inflammation. Over time, that inflammation can change the stomach lining. Those changes can become cancer. A simple breath, stool, or blood test can find H. pylori. Antibiotics can clear it. That makes it one of the few cancer risk factors you can directly remove.
Long-term H. pylori infection is a major, treatable risk factor for stomach cancer.
Diet and lifestyle
Diets high in salted, smoked, or pickled foods are linked to higher stomach cancer risk. Diets rich in fresh fruits and vegetables are linked to lower risk. Smoking also raises risk. Chemicals in tobacco reach the stomach lining and add to damage from other causes. Heavy alcohol use may add some risk too.
Who else is at higher risk
Risk rises with age. Stomach cancer is more common in men than in women. A family history of stomach cancer raises risk, and so do certain inherited gene changes. Some stomach conditions raise risk as well, including chronic gastritis and pernicious anemia, both of which cause long-term inflammation of the stomach lining. People who have had part of their stomach removed in the past also carry somewhat higher risk.
Having a risk factor is not a diagnosis
Most people with one or more of these risk factors never get stomach cancer. Risk factors describe a pattern seen across large groups of people, not a prediction for any one person. Still, knowing your own risk factors helps you and your doctor decide whether testing makes sense, especially if you also have ongoing symptoms.
Lowering your risk
You cannot change your age, sex, or family history. But several things are within your control. Getting tested and treated for H. pylori is the most direct step, especially if you have a family history of stomach cancer. Not smoking helps too. So does eating more fresh produce and less salted or smoked food. If you have ongoing stomach symptoms, ask your doctor whether H. pylori testing makes sense for you.
What to ask your team
Ask whether you should be tested for H. pylori infection. Ask whether your family or personal history puts you at higher risk. Ask whether treating an infection would lower your risk if you have one. Ask what symptoms should prompt you to come back for evaluation.
A few more factors to know
A few other things are linked to stomach cancer risk. People with type A blood have a somewhat higher risk, for reasons that are not fully understood. Stomach polyps, a rare condition called Menetrier disease, and past exposure to Epstein-Barr virus are also linked to some cases. Certain jobs, including coal, metal, and rubber work, carry higher risk from workplace exposures. Smoking is one of the stronger modifiable factors: NCI states that people who smoke have a higher risk of stomach cancer than nonsmokers.
Where you live matters too
Stomach cancer is more common in East Asia, Eastern Europe, and parts of Central and South America. It is less common in North America and Africa. Diet, rates of H. pylori infection, and food preservation methods common in a region all likely play a role. This is one reason stomach cancer screening is more common in some countries than others, even though it is not routine in the United States.
Sources
Words to know
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Common questions
What is the biggest risk factor?
Long-term infection with H. pylori, a common stomach bacterium, is a major risk factor. It causes long-lasting inflammation that can lead to cancer over many years.
What dietary factors matter?
Diets high in salted, smoked, or pickled foods, and low in fruits and vegetables, are linked to higher stomach cancer risk.
Who else is at higher risk?
Risk rises with age and is higher in men. Smoking, a family history of stomach cancer, and certain stomach conditions also raise risk.
Can risk be lowered?
Treating H. pylori infection, not smoking, and a diet rich in fruits and vegetables may help lower risk.
Questions to ask your doctor
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Last updated: 2026-08-18Next planned review: 2027-07-07
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How this page was created
Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes. We do not employ clinicians and do not intend to — our work is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and checked line by line against the sources listed on it. That confirms the sources support what the page says. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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