In the United States, research has shown that stomach cancer disproportionately impacts certain racial/ethnic groups. Stomach cancer occurs more often among Black, Hispanic, Asian/Pacific Islander, and American Indian/Alaska Native individuals. Within these populations, certain sub-groups present higher rates of stomach cancer; for example, studies have shown Black men and young Hispanic females to have higher rates of gastric cancer.

Stomach cancer is often more commonly diagnosed in men than in women (nearly two times as many diagnoses).

Although stomach cancer can be diagnosed at any age, the risk generally increases with age.

Helicobacter pylori (H.pylori) is a bacterium that infects the stomach lining, and chronic infection of the stomach lining with H. pylori is a major risk factor for stomach cancer. The bacterium is typically spread through direct person-to-person contact with saliva, vomit, or stool. Common places of exposure include close contact with infected individuals, shared living spaces, and contaminated food or water.

While many infected individuals may not show symptoms, treating H. pylori infections can reduce the risk of developing stomach cancer.

The risk of stomach cancer is increased in people who have

• Chronic atrophic gastritis: thinning of the stomach lining caused by long-term inflammation of the stomach
• Atrophic gastritis with intestinal metaplasia: a condition in which the cells that line the stomach are replaced by cells that normally line the intestines
• Epstein-Barr virus (EBV): a virus to which 5%-10% of all gastric cancers are associated
• Pernicious anemia: an autoimmune condition in which the intestines can’t properly absorb vitamin B12, resulting in a low red blood cell count
• Obesity: excess body weight
• Gastroesophageal reflux disease (GERD): a condition in which stomach acid repeatedly flows back into the esophagus

The risk of stomach cancer is increased in people who have:

• A first-degree relative (parent, sibling, or child) who has had stomach cancer
• An inherited cancer syndrome (hereditary diffuse gastric cancer, gastric adenocarcinoma and proximal polyposis of the stomach, familial intestinal gastric cancer, etc.)
• Type A blood

Dietary choices, such as not eating fruits and vegetables, or eating poorly preserved or highly salted foods, may increase the chance of gastric cancer.

Tobacco use, particularly smoking, can make individuals more likely to develop stomach cancer. Quitting smoking can gradually reduce this risk.

There are environmental and occupational factors that have been found to increase the likelihood of gastric cancer development. Working in certain industries, such as rubber or coal, or exposure to radiation have been linked to gastric cancer, but being aware and taking appropriate precautions may help mitigate potential risks.