Polyps are extra pieces of tissue growing from the lining of the colon, says the National Digestive Diseases Information Clearinghouse. Polyps can stick out into the colon and look somewhat similar to mushrooms, or they can lie flat against the wall of the colon. Colon and rectal cancer usually begin as polyps, but polyps themselves are not cancer; they are called "precancerous" growths.
Although only about 10 percent of colon polyps develop into cancer, more than 95 percent of colorectal cancers develop from polyps, says John Hopkins Medicine Health Alert. Colon polyps grow slowly and may take over a decade to develop into cancer.
The cause of polyps is unclear. Individuals who are overweight, eat a lot of processed meats, drink a lot of alcohol and do not get sufficient exercise are more likely to develop polyps, notes NDDIC. Because removing polyps can prevent colorectal cancer from developing, most doctors recommend removing all colon polyps. Colon polyps can be painlessly removed during routine colonoscopy or sigmoidoscopy procedures, according to John Hopkins.
Colon polyps are usually asymptomatic; they can only be detected by screening tests. The U.S. Preventive Services Task Force recommends that all adults between the ages of 50 to 75 undergo some type of regular screening for colon polyps. A variety of screening methods are available.