About Your Care and Condition
The colon and rectum are the two main parts of the large intestine. Although the colon is only one part of the large intestine, because most of the large intestine consists of colon, the two terms are often used interchangeably. The large intestine is also sometimes called the large bowel.
Digestive waste enters the colon from the small intestine as a semi-solid. As waste moves toward the anus, the colon removes moisture and forms stool. The rectum is about six inches long and connects the colon to the anus. Stool leaves the body through the anus. Muscles and nerves in the rectum and anus control bowel movements.
Colorectal cancer describes any cancers of the bowel, including those of the large intestines, colon, rectum and appendix. Rectal cancer begins in the rectum, which is the last several inches of the colon.