Colorectal Cancer Overview
Colorectal cancer is cancer that occurs in the colon or rectum. Colorectal cancer includes cancer of the colon (colon cancer), cancer of the rectum (rectal cancer) and cancer of the anus (anal cancer).
- The colon and rectum are parts of the digestive system . They form a long, muscular tube called the large intestine (also called the large bowel). The colon is the first 4 to 5 feet of the large intestine, and the rectum is the last several inches. The anus is the bottom.
- Partly digested food enters the colon from the small intestine. The colon removes water and nutrients from the food and turns the rest into waste (stool). The waste passes from the colon into the rectum and then out of the body through the anus.
This picture (courtesy of National Cancer Institute) shows the colon, rectum and anus.
Most colorectal cancers develop first as colorectal polyps, which are growths inside the colon or rectum that may later become cancerous.
The process used to find out if cancer has spread within the colon/rectum or to other parts of the body is called staging. The information gathered from the staging process determines the stage of the disease. It is important to know the stage in order to plan treatment.