Several different types of cancer can occur in the stomach. The most common type is called adenocarcinoma, which refers to the way the cancer looks under the microscope. There are several types of adenocarcinoma. Because other types of gastric cancer occur much less frequently, this article focuses on adenocarcinoma. Adenocarcinoma of the stomach is a common cancer of the digestive tract worldwide, although it is relatively uncommon in the US. It occurs most frequently in men over 40 years old. The incidence of this form of gastric cancer is extremely high in Japan, Chile, and Iceland. The incidence of most types of gastric adenocarcinoma in the US has declined over the years. Experts think the decrease may be related to reduced intake of salted, cured, and smoked foods, and increased vitamin C consumption. However, the incidence of adenocarcinoma in the high part of the stomach where it connects with the esophagus has increased markedly, along with an increase in cancers of the lower esophagus. The reason for this increase is unknown.
Diagnosis is often delayed by the absence of symptoms in early disease or by self-treatment of symptoms that may be common to other, less serious gastrointestinal disorders (bloating, gas, and a sense of fullness).
Risk factors for gastric cancer are a family history of gastric cancer, Helicobacter pylori infection, blood type A, a history of pernicious anemia, a history of chronic atrophic gastritis, a condition of decreased gastric acid, and a prior history of adenomatous gastric polyp. | 
Gastrointestinal Cancer, Endocrine and Oncologic Surgery
