Oncologists John Strickler, MD, and Fatima Rangwala, MD, answer frequently asked questions about colon cancer prevention and detection.

Fatima Rangwala, MD

Can screening really prevent colon cancer?

Rangwala: Yes. Tumors in the colon begin as non-cancerous growths called polyps. The detection and removal of colon polyps can prevent colon cancer.

Therefore, screening for colon cancer is very important, not only because it is so effective, but also because colon cancer tumors may not produce any detectable symptoms until they’ve advanced to a life-threatening stage.

Can changing my diet help prevent colon cancer?

Rangwala: Yes. Studies have shown that diets full of folate, calcium, and vitamin D are associated with lower rates of colon cancer.

John Strickler, MD

Exercise is important as well, and can cut your risk of developing colorectal cancer by nearly 50 percent.

Is a colonoscopy the only test for colon cancer?

Strickler: Colonoscopy has long been the gold standard for catching colorectal cancer, but it is not the only screening test.

Men and women should have some type of screening generally starting at age 50: yearly testing to check for blood in the stool, a flexible sigmoidoscopy every five years, or a colonoscopy every 10 years.

Fecal occult blood tests analyze stool samples for blood, which may signal polyps or cancer. They involve placing small amounts of stool on special cards that are examined under a microscope.

Flexible sigmoidoscopy is a procedure in which a physician looks at the lower third of the colon and surrounding areas with a small, tube-like camera. Performed in a doctor’s office with minimal sedation, sigmoidoscopy will detect most colon cancers.

Colonoscopy is the best way to visualize the entire colon. It involves threading a luminous tube into and around the colon to detect abnormalities.

Virtual colonoscopy is a less invasive alternative to the standard procedure. It uses a CT scan to produce pictures of the colon for analysis. Data on the accuracy of virtual versus normal colonoscopies have been mixed -- and, as with sigmoidoscopy, any irregularities mean you’ll also have to undergo a full colonoscopy.