Risk Factors of Colon Cancer risks

People at increased risk of colon cancer need to be screened more aggressively than other people. Here are the major risk factors for colon cancer and the screening recommendations for people who have those factors:

Colon cancer or polyps in a first-degree relative (parent, sibling, or child). Undergo colonoscopy or a double-contrast barium enema every five years, starting either at age 40 or 10 years before the youngest case in the family, whichever is earlier.

Colon cancer or polyps in a second-degree relative (aunt, uncle, grandparent, or cousin). Consider starting screening at age 40 rather than 50.

Familial adenomatous polyposis (FAP) or hereditary nonpolyposis colon cancer (HNPCC) in a first- or second-degree relative. People with FAP -- a very rare genetic abnormality that causes hundreds and sometimes thousands of polyps, usually starting in the teenage years--nearly always develop colon cancer by age 40.

People with a family history of FAP should talk with a genetic counselor about being tested for the gene at puberty and possibly even considering preventive surgery if they test positive.

Those who decline the genetic test should undergo sigmoidoscopy every year starting at puberty. People with a family history of HNPCC, a more common genetic abnormality that increases susceptibility to colon cancer without rampant proliferation of polyps, should talk with a genetic counselor.

If the genetic test is positive, or if they forgo the test, they should undergo colonoscopy every one or two years starting in their 20s, then annually after age 40.

Personal history of ulcerative colitis. Individuals who've had this disease for more than about a decade should undergo colonoscopy every one to two years. Last updated Nov 26/06