Polyps are mushroom-shaped growths on the inner lining of the large bowel. Although they are non-cancerous, one type of polyp called adenoma is the precursor of colon cancer. If untreated, some adenoma will grow bigger and become cancerous in a number of years. Polyposis is a hereditary condition in which an individual develops hundreds of polyps in the large bowel. For an average person, the risk of colon cancer increases with age from 50 years onwards.
Individuals having close relatives with colon cancer are at-risk.
The risk increases with increasing number of affected close relatives. A person with a history of large or numerous colonic adenoma or a history of extensive ulcerative colitis for more than ten years are also at risk of colon cancer. Genetic testing is helpful in pinpointing this condition.