Studies have found the following risk factors for stomach cancer:
Helicobacter pylori infection
People who have conditions associated with long-term stomach inflammation (such as the blood disease pernicious anaemia) are at increased risk of stomach cancer. Also, people who have had part of their stomach removed may have long-term stomach inflammation and increased risk of stomach cancer many years after their surgery.
Long-term inflammation of the stomach
Smokers are more likely than nonsmokers to develop stomach cancer. Heavy smokers are most at risk.
Close relatives (parents, brothers, sisters, or children) of a person with a history of stomach cancer are somewhat more likely to develop the disease themselves. If many close relatives have a history of stomach cancer, the risk is even greater.
Studies suggest that people who eat a diet high in foods that are smoked, salted, or pickled have an increased risk for stomach cancer. On the other hand, people who eat a diet high in fresh fruits and vegetables may have a lower risk of this disease.
A lack of physical activity may increase the risk of stomach cancer.
Also, people who are obese may have an increased risk of cancer developing in the upper part of the stomach.