A risk factor is something that increases your likelihood of getting a disease or condition.

It is possible to develop stomach cancer with or without the risk factors listed below. However, the more risk factors you have, the greater your chance of developing stomach cancer. If you have a number of risk factors, ask your doctor what you can do to reduce your risk.

In general, risk increases in people over 50 years old, but most stomach cancers are found in people aged 60-85 years old. Stomach cancer is twice as likely to affect men than women. Stomach cancer risk is also higher in people of eastern Asia, eastern Europe, and South American descent.

Stomach cancer has been strongly associated with lifestyle factors. The following factors may increase the risk:

  • Smoking— Tobacco contains cancer-causing agents (carcinogens) that can cause irritation and cellular changes in the stomach lining. The top part of the stomach closest to the esophagus is most the vulnerable. The risk of cancer increases with the amount of tobacco used and the number of years as a tobacco user. All forms of tobacco are strongly associated with stomach cancer, nearly doubling the risk of the disease. The risk drops once tobacco use is stopped.
  • Diet—Diets high in red meat, excess salt, or lack of fruits and vegetables increase the risk. Risk is higher in those who eat salted, preserved, pickled, smoked, or cured meats. Foods with nitrates such as deli or processed meats also increase cancer risk.
  • Excessive alcohol use—Alcohol itself is not considered a carcinogen, but three or more drinks a day may cause irritation to the stomach lining, especially in the area closest to the esophagus. The risk is compounded in those who smoke.
  • Occupational exposures—Coal, metal, and rubber industry employees face the highest risk of stomach cancer in the workplace.

Several medical conditions may increase the risk of stomach cancer. These include:

  • Helicobacter pylori infection (H. pylori)— A type of bacteria known to cause gastric ulcers and chronic inflammation of the stomach lining. The longer that the infection is present, the more risk increases. H. pylori is easily treated with antibiotics.
  • Barrett's esophagus—An abnormal change in the cells of the lower end of the esophagus. The change is thought to be caused by damage from gastroesophageal reflux disease (GERD). Barrett's esophagus is also a risk factor for esophageal cancer.
  • Chronic gastritis—Chronic inflammation in the stomach lining leads to a loss of normal glands. This can lead to a reduction in substances the stomach needs to function normally.
  • Obesity—Obesity is associated with Barrett's esophagus and GERD. Excess weight causes more pressure on the stomach and lower esophagus. The top part of the stomach is most affected.
  • Stomach polyps—Abnormal growths can sometimes turn into cancer if left untreated. May be caused by Peutz-Jeghers syndrome.
  • Previous stomach surgery—Risk increases several years after previous surgery on the stomach or vagus nerve. Both can lead to a reduction in stomach acid production.
  • Pernicious anemia—A rare disorder caused by a lack of intrinsic factor. Instrinsic factor is needed to absorb vitamin B12 into the digestive tract. Vitamin B12 is essential to make red blood cells.
  • Epstein-Barr virus (EBV) infection—Causes mononucleosis and may result in persistent infection that affects the immune system.

Stomach cancer tends to run in families. Other cancers with genetic factors may also increase the risk. These include

  • Hereditary non-polyposis colorectal cancer (Lynch syndrome) or familial adenomatous polyposis, which are also associated with colon cancer
  • Having the BRCA1 or BRCA2 gene, which are associated with breast cancers in women and men
  • Li-Fraumeni syndrome—Caused by a mutation in the TP53 gene and may be associated by stomach cancer at younger ages.