Colorectal cancer can develop in one of two areas of the digestive system:

• Large bowel (colon)
• Back passage (rectum)

The walls of the colon and rectum are made up of layers of body tissue. Most colon and rectal cancers start in the inner lining of the bowel.

The cancer grows from a polyp in the bowel. Many polyps are benign (harmless). However, if left untreated they can develop into cancerous tumours. Removing polyps can prevent cancerous tumours in the bowel.

If you experience symptoms of bowel cancer, you should always see your GP.