Overview

Most (85%) cases of gastric cancer are adenocarcinomas that occur in the lining of the stomach (mucosa). Approximately 40% of cases develop in the lower part of the stomach (pylorus); 40% develop in the middle part (body); and 15% develop in the upper part (cardia). In about 10% of cases, cancer develops in more than one part of the organ.

Stomach cancer can spread (metastasize) to the esophagus or the small intestine, and can extend through the stomach wall to nearby lymph nodes and organs (e.g., liver, pancreas, colon). It also can metastasize to other parts of the body (e.g., lungs, ovaries, bones).

Incidence
According to the National Cancer Institute (NCI), approximately 760,000 cases of stomach cancer are diagnosed worldwide and more than 24,000 cases are diagnosed in the United States each year. Incidence is highest in Japan, South America, Eastern Europe, and parts of the Middle East. Worldwide, stomach cancer is the second leading cause of cancer-related deaths.

Changes in diet and food preparation have led to a recent decrease in the incidence of cancer of the lower stomach (distal gastric cancer). However, incidence of cancer of the upper stomach (proximal gastric cancer) has increased, primarily as a result of the prevalence of obesity and gastroesophageal reflux disease (GERD).

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