How do I keep from getting colon cancer?
Several options exist to reduce your risk of dying from colon cancer. The recommended choices are the fecal occult blood test, flexible sigmoidoscopy and colonoscopy.
The stool for blood test (also called the FOBT test) requires that several stool samples be sent for analysis to determine if blood is present in the stool. In a study in the New England Journal of Medicine, the FOBT test identified only 23.9% of patients who had an advanced pre-cancerous lesion as determined by a colonoscopy performed right after the FOBT test. This test needs to be repeated every two years. It reduces death from colon cancer as compared to no screening at all. It is considered a "cancer detection" test, and not a "cancer prevention" test. This is because cancers tend to bleed more often than do polyps that have yet to become cancerous. The Asia Pacific consensus recommendations for colorectal cancer screening suggest that this test is appropriate for use in resource-limited countries.
Flexible sigmoidoscopy can be considered a colonoscopy that stops half-way through the colon. In combination with the FOBT test, flexible sigmoidoscopy can detect about 75.8% of advanced pre-cancerous growths. Colon cancers are distributed about equally throughout the entire colon. This test is an improvement over FOBT alone, but better options exist.
CT colonography involves taking images of the colon with a series of x-rays. It compares favorably to colonoscopy when the CT is perfomed at an expert center with specialized radiologists. Its disadvantages include radiation exposure, the need to take a full bowel preparation (just like with colonoscopy), a high financial cost, and the requirement to take another bowel preparation and to undergo a follow-up colonoscopy for definitive diagnosis and potential treatment if any suspicious findings are noted on the CT colonography. This test is not currently a preferred colorectal cancer screening test, but is a viable test to be performed every five years in patients who decline colonoscopy. That said, access to this test is severely limited in Ontario.
Colonoscopy is the "preferred" screening test for colorectal cancer prevention according to the American College of Gastroenterology Guidelines for Colorectal Cancer Screening 2008. It reduces the incidence of colorectal cancer by 70% to 80%. The benefits of colonoscopy are that it is widely available, it examines the entire colon, it allows for single-session diagnosis and treatment, and it need not be uncomfortable when sedation is used.
