Gastric (stomach) cancer (adenocarcinoma or less commonly, lymphoma), can occur in any part of the stomach. As the cancer grows, it can spread through the stomach wall and into nearby organs, such as the oesophagus, liver, pancreas and small intestine (duodenum). Because your stomach is able to expand when you eat, it can easily expand to accommodate a growing tumour. Gastric cancer is most common in males over 40. A cure is possible with early diagnosis and surgical removal of all or part of the stomach, but diagnosis is often delayed because there are few distinct symptoms before the cancer spreads.
First symptoms can mimic indigestion or ulcers. You might have stomach discomfort or dyspepsia (heartburn) that is relieved by antacids, and you might feel full after eating a small amount. You can lose your appetite and lose weight because of the indigestion.
As the tumour grows, it erodes blood vessels, and blood enters the intestinal tract. Your stool may become dark and "tarry" looking if there is a lot of bleeding, but small amounts are hidden and detected only by testing your stool for occult (hidden) blood. If bleeding is severe, you might pass frank blood in your stool or vomit blood. Blood tests might show you are anaemic from blood loss.
If the tumour partially or completely obstructs the pylorus (the area connecting the stomach and the duodenum of the small intestine), you might experience nausea and vomiting after eating because your stomach is unable to empty.
Dysphagia (difficulty swallowing) can occur, especially if the tumour is near or spreading into the oesophagus, which carries food from the mouth to the stomach. Sometimes the tumour obstructs the end of the oesophagus where it connects to the stomach. You might find yourself eating slowly, regurgitating or choking on your food.
Gastric cancer is associated with a history of chronic Helicobacter pylori infection and stomach ulcers. Other risk factors include smoking and a diet high in nitrates (such as found in smoked foods) or sodium and low in vitamin C.
If you are over 55 years of age and have a new or sudden onset of indigestion or an unhealing ulcer, you should have testing, such as an endoscopy and stool tests for occult blood. You might need a biopsy (surgical removal of a small amount of tissue from the stomach) to differentiate between gastric ulcers and gastric cancer, because the lesions in the early stages of cancer are similar in appearance to ulcers.