The exact cause of bowel cancer is unknown.  Current research suggests that a combination of genetic or inherited factors, plus environmental influences are the most likely causes.

Researchers believe that bowel cancer is caused by changes to the cells lining the bowel wall. These cells become polyps, which may then develop into cancer cells. These changes may take between 5-10 years to develop and the causes are not completely understood. There are many types of polyps, but the most important one to detect and remove is called an ‘adenoma’.

Bowel cancer is more common in developed countries, and it is thought that a high animal-fat, highly processed diet may be associated with an increased incidence of bowel cancer, and that an increased amount of dietary fibre may reduce the incidence.