Stomach cancer, or gastric cancer, is cancer that starts in the stomach. Gastric cancer usually begins in cells in the inner layer of the stomach. Over time, the cancer may invade more deeply into the stomach wall. A stomach tumor can grow through the stomach's outer layer into nearby organs, such as the liver, pancreas, esophagus or intestine.
Stomach cancer cells can also spread by breaking away from the original tumor. They enter blood vessels or lymph vessels, which branch into all the tissues of the body. The cancer cells may be found in lymph nodes near the stomach. The cancer cells may attach to other tissues and grow to form new tumors that may damage those tissues. The spread of cancer is called metastasis, or metastatic cancer.
Diagnosis and Prognosis
Diagnosis of stomach cancers are often delayed because symptoms may not occur in the early stages of the disease, or because patients self-treat symptoms that may be common to other, less serious gastrointestinal disorders (such as bloating, gas, heartburn and a sense of fullness).
The outlook (prognosis) for gastric cancer varies widely. Tumors in the lower stomach are more often cured than those in the higher area (gastric cardia or gastroesophageal junction). The depth to which the tumor invades the stomach wall and whether lymph nodes are involved influence the chances of cure.
In circumstances in which the tumor has spread outside of the stomach, cure is not possible and treatment is directed toward improvement of symptoms.
The most common type of gastric cancer worldwide is called adenocarcinoma, which starts from one of the common cell types found in the lining of the stomach. There are several types of adenocarcinoma, and globally it is the most common cancer of the digestive tract (although it remains relatively uncommon in the United States). It occurs most frequently in men over 40 years old.
This form of gastric cancer is extremely common in Japan, Chile and Iceland. The rate of most types of gastric adenocarcinoma in the United States has declined over the years. Experts think the decrease may be related to reduced intake of salted, cured, and smoked foods. Gastric adenocarcinoma occurs most frequently in men over 40 years of age.