Understanding Colorectal Cancer Cancer that begins in the colon is called colon cancer, and cancer that begins in the rectum is called rectal cancer. Cancers affecting either of these organs may also be called colorectal cancer. The exact causes of colorectal cancer are not known.
Colorectal cancer is more likely to occur as people get older.
This disease is more common in people over the age of 50. However, colorectal cancer can occur at younger ages, even, in rare cases, in the teens. Colorectal cancer seems to be associated with diets that are high in fat and calories and low in fiber. Researchers are exploring how these and other dietary factors play a role in the development of colorectal cancer. Polyps are benign growths on the inner wall of the colon and rectum.