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| Colon Cancer Research |
Cancer of the colon, a common form of cancer, is a disease in which cancer (malignant) cells are found in the tissues of the colon. The colon is part of the body's digestive system. The purpose of the digestive system is to remove nutrients (vitamins, minerals, carbohydrates, fats, proteins, and water) from the foods eaten and to store the waste until it passes out of the body. The digestive system is made up of the esophagus, stomach, and the small and large intestines. The last 6 feet of intestine is called the large bowel or colon. Genes are markers in cells associated with hereditary traits. Abnormal genes have been found in patients with some forms of colon and rectal cancer. Tests are being developed to determine who carries these genes long before cancer appears. Screening tests (such as a rectal examination, proctoscopy, and colonoscopy) may be done regularly in patients who are at higher risk to get cancer. These tests may be done in patients who are over age 50; who have a family history of cancer of the colon, rectum, or of the female organs; who have had small noncancerous growths (polyps) in the colon; or who have a history of ulcerative colitis (ulcers in the lining of the large intestines). A doctor may order these tests to look for cancer if there is a change in bowel habits or if there is any bleeding from the rectum. A doctor will usually begin by giving the patient a rectal examination. In a rectal examination the doctor, wearing thin gloves, puts a greased finger into the rectum and gently feels for lumps. The doctor may then check the material collected from the rectum to see if there is any blood in it. The doctor may also want to look inside the rectum and lower colon with a special instrument called a sigmoidoscope or a proctosigmoidoscope. This examination, called a proctoscopy or procto examination, finds about half of all colon and rectal cancers. The test is usually done in a doctor's office. Some pressure may be felt, but usually with no pain. The doctor may also want to look inside the rectum and the entire colon (colonoscopy) with a special tool called a colonoscope. This test is also done in a doctor's office. Some pressure may be felt, but usually with no pain. If tissue that is not normal is found, the doctor will need to cut out a small piece and look at it under the microscope to see if there are any cancer cells. This is called a biopsy. Biopsies are usually done during the proctoscopy or colonoscopy, in a doctor's office. The prognosis (chance of recovery) and choice of treatment depend on the stage of the cancer (whether it is just in the inner lining of the colon or if it has spread to other places) and the patient's general state of health. After treatment, a blood test (to measure amounts of carcinoembryonic antigen or CEA in the blood) and x-rays may be done to see if the cancer has come back. |
PDQ® information licensed from the NCI. For complete PDQ summaries, visit the NCI at http://cancernet.nci.nih.gov/ |
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