What is colorectal cancer?

Most colorectal cancers start in cells that line the inside of the colon or the rectum. The colon and rectum make up the large intestine (large bowel). The large intestine is the last part of the digestive system. Organs of the digestive system break down food, absorb nutrients and help pass waste out of the body.

Food is digested in the stomach and the small intestine. As the stomach and small intestine remove nutrients from food, it becomes a watery mass. The watery mass passes through the small intestine into the colon. The colon absorbs the water as the semi-solid waste travels through it to the rectum. This waste material is known as feces or stool. The stool is stored in the rectum. When you have a bowel movement, the stool leaves the body through the anus.