Stomach cancer usually presents in patients between 50 to 70 years of age although younger patients have been to known to be affected as well. It is more common in men with Singapore males estimated to have a lifetime risk of 1:50. Known risk factors for gastric cancer include Helicobacter pylori infection of the stomach and consumption of salted or preserved (cured/smoked/pickled) foods. Smoking and high salt-intake are also associated with a higher incidence of gastric cancer.

The syndrome of hereditary diffuse gastric cancer (HDGC) involves a specific gene mutation which is uncommon. However, other patients with a strong family history of gastric cancer may also be at a slightly higher risk of developing stomach cancer. Certain hereditary syndromes such as familial adenomatous polyposis (FAP), Li-Fraumeni syndrome, hereditary nonpolyposis colorectal cancer (HNPCC) and Peutz-Jeghers syndrome also increase the risk of stomach cancer.

Prevention of gastric cancer usually focuses on reduction of risk factors such as smoking and consumption of preserved foods, and increasing the proportional intake of fresh fruit and vegetables.