Due to the human genome project and other genetic research, tests for mutation which cause diseases have been developed. The list of these illnesses include several types of cancer. Doctors have estimated that as many as 3,000 diseases are due to mutations in the genome. These diseases include several types of colon cancer in which three different genetic tests have been already developed. Debates have arisen on whether these tests should be used regularly or not. Questions including the patients= rights of privacy and the possibility of loss of health or life insurance have been argued over in both the media and political arena.
Colon cancer develops in the part of the gastrointestinal tract that absorbs water and minerals before waste products are disposed via the rectum. In women endometrial cancer is related to colon cancer. This type of cancer is the second leading cause of death due to cancer in the United States. Over one-hundred fifty thousand individuals will be diagnosed this year and this cancer will probably be responsible for about 47,900 deaths in 1999 (http://www.cancer.org). Most colon cancers are adenocarcinomas that develop from the glandular cells. Ninety percent of all colon cancer cases will develop in individuals after 50 years of age. Ninety percent of all tumors arise from polyps that are commonly found in people older than 50. Prevention includes regular exercise and a diet high in fiber. The most important risk factor is age. Medical screening includes a yearly blood occult test after age 50 and a colonoscopy every 3 years after age 50. Regular screening detects polyps that have become precancerous. If regular screening is not done, the cancer is not detected until blood is found in the feces or other symptoms appear including intestinal blockage. By this time the tumor has developed and a section of the colon must be removed. Only 37% of all colon cancers are found in the early stages of the disease. This cancer can easily move and form colony tumors in other organs. After this occurs, the survivorship drops drastically. Less than 10% of colon cancers are caused by inherited gene mutations in which tests have been designed.
The genetic tests developed for colon cancer include hereditary nonpolypsis colon cancer (HNPCC), familial adenomatous polyposis (FAP), and a mutation related to FAP that is only found in Jews of Eastern European descent. These two types of colon cancer are among the rarest types of colon cancer HNPCC has only a few polyps present or occasionally no polyps are present. In HNPCC, colorectal cancer occurs primarily on the right side of the colon whereas most sporadic colon cancer is left-sided. The chance of developing other cancers increases with HNPCC. These include uterus, ovary, stomach, urinary tract, small bowel, and bile ducts. Another name for HNPCC is Lynch=s syndrome. If a person is positive for the genetic test, they are 85% likely to develop cancer.
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