The colon and rectum are parts of the body’s digestive system, which removes nutrients from food and stores waste until it passes out of the body.
Together, the colon and rectum form a long, muscular tube called the large intestine (also called the large bowel). The colon is the first six feet of the large intestine, and the rectum is the last eight to 10 inches.
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 the age of 50, who have a family history of cancer of the colon, rectum, or of the female organs, who have had small non–cancerous 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.