Doctors cannot determine with certainty the cause of any particular case of gastric cancer, Mayo Clinic says. Known risk factors for stomach cancer include dietary factors such as excessive consumption of smoked or pickled foods, consumption of foods contaminated with aflatoxin fungus, and insufficient intake of fruits and vegetables. Other risk factors include Helicobacter pylori infection, pernicious anemia, smoking, a family history of stomach cancer and chronic stomach inflammation.
Doctors generally suspect gastric cancer on the basis of its symptoms, which can include feeling full after small meals, severe indigestion, stomach pain, unexplained weight loss and fatigue, Mayo Clinic says. Other symptoms include persistent vomiting and severe heartburn. Doctors use exploratory tests to find the cause of these symptoms, including imaging tests such as a CT scan or barium swallow. Doctors often also perform an endoscopy, where a thin tube containing a small camera is inserted through the esophagus to observe the interior of the stomach. The endoscope has tools attached that allow the doctor to take tissue samples of suspicious areas for testing.
If doctors find cancer, treatment depends in part on how advanced the cancer is, Mayo Clinic explains. To determine the extent of gastric cancer, doctors often use imaging tests, such as positron emission tomography, and may also use exploratory surgery to see if the cancer extends into the rest of the abdomen.