Introduction to UGI Cancer
Collectively, cancers of the esophagus, stomach, and small intestine are referred to as upper gastrointestinal tract (UGI) cancers. UGI cancers represent the second most common site and cause of death among the digestive system cancers.
The American Cancer Society estimates that during 2003, approximately 13,900 new esophageal cancer cases will be diagnosed in the United States (10,600 men and 3,300 women). This disease is about 3 times more common among men than women and almost 3 times more common among African Americans than whites.
There are two main types of esophageal cancer: squamous cell carcinoma and adenocarcinoma. The majority of cancers in the upper two-thirds of the esophagus are squamous cell carcinoma in nature. Adenocarcinoma starts in glandular tissue, which normally does not cover the esophagus. It usually occurs in the lower esophagus, near the stomach. Before an adenocarcinoma can develop, glandular cells must replace an area of squamous cells, for example as in Barrett esophagus.
Squamous cell carcinoma is the most common type of cancer of the esophagus among African Americans, while adenocarcinoma is more common in whites. Cancer of the esophagus is much more common in some regions of the world. For example, esophageal cancer rates in Iran, northern China, India, and southern Africa are 10 to 100 times higher than that in the United States.
Stomach cancer (also called gastric cancer) can develop in any part of the stomach and may spread throughout the stomach and to other organs. It may grow along the stomach wall into the esophagus or small intestine. It also may extend through the stomach wall and spread to nearby lymph nodes and to organs such as the liver, pancreas, and colon. Stomach cancer also may spread to distant organs, such as the lungs, the lymph nodes above the collar bone, and the ovaries. Each year, about 24,000 people in the United States are diagnosed with cancer of the stomach.
Most of stomach cancers are adenocarcinomas, arising in the glandular cells in the stomach lining. These glandular cells normally produce mucus and digestive enzymes. Other stomach cancers may include squamous cells cancers, lymphomas, sarcomas, and neuroendocrine tumors.
Small Intestine Cancer
Cancer of the small intestine, a rare cancer, is a disease in which cancer cells are found in the tissues of the small intestine. Each year US doctors diagnose about 1200 malignant small intestine tumors. This is a small number relative to the frequency of tumors in other parts of the GI tract.
The majority of cancers of the small intestine are adenocarcinomas (50% or more) and commonly start in the duodenum, jejunum, and the part of the small intestine nearest the stomach. These cancers often grow and obstruct the bowel.
Leiomyosarcomas, another type of small intestine cancer, occur most often in the ileum. Some 20% of malignant lesions of the small intestine are carcinoid tumors, which occur more frequently in the ileum than in the duodenum or jejunum. It is uncommon to find malignant lymphoma as a solitary small intestinal lesion.