What is colorectal cancer?
Colorectal cancer starts in the colon or the rectum. Referred to as colon cancer or rectal cancer, depending on where they start, they are grouped together as colorectal cancer as they have many elements in common.
Most colorectal cancers begin as polyps, which are growths on the inner lining of the colon or rectum. Not all polyps become cancerous, but some types of polyps can become cancerous over time.
Most colorectal cancers are adenocarcinomas. According to the American Cancer Society, these cancers start in cells that make mucus to lubricate the inside of the colon and rectum. This is the most common type of colorectal cancer, though some sub-types may have a worse prognosis (potential outcome) than others.
Other, less common types of colorectal cancer include:
- Carcinoid tumors
- Gastrointestinal stromal tumors (GISTs)