Colon polyps are precursors of colon cancer and are responsible for 90 to 95 percent cases of colon cancer. A colon polyp is any grossly visible protrusion from the mucosal surface of the colon. The incidence of colon polyps increases rapidly with age. About 60 percent of Americans older than 65 have developed colon polyps.
The are two major types of colon polyps: benign polyps, which are very unlikely to become cancer, and adenomatous polyps (also known as adenomas), which have the potential to become cancer. Benign polyps include several distinct categories, such as hyperplastic polyps, mucosal polyps, inflammatory polyps and submucosal polyps.
The average size of polyps is 6 to 7 mm. Overall, 45 percent of polyps are smaller than 5 mm, 40 percent of polyps are between 5 and 10 mm, and 15 percent are larger than 10 mm.
The incidence of colon polyps increases exponentially with age and is a function of various risk factors including gender, body mass index, family history, aspirin use, smoking and physical activity.
Colon polyps can be detected and removed during a colonoscopy.
The distribution of polyps shifts from the distal colon to the proximal colon with increasing age.
The risk of malignant transformation of adenomatous polyps increases with size. A 20 mm adenoma has 20 percent chance of becoming cancer.
A person typically does not have more than three to five colon polyps. However, patients diagnosed with familial adenomatous polyposis syndrome may have more than 100 polyps.