There are many reasons people develop bowel cancer. It is difficult to give one reason, however, for most people it is their age and their diet that contribute to the development of bowel cancer. The risk is greater for people who have a family history of bowel cancer or polyps, who have had an inflammatory bowel disease such as Crohn’s disease or ulcerative colitis, or who have previously had polyps in the bowel.
The development of bowel cancer generally takes many years. It starts as a tiny growth called a polyp on the inside wall of the bowel. It can grow there for a long time before it undergoes changes to become cancerous and then spreads to other parts of the body.
Last reviewed: May 2018