Why You Need a Colonoscopy

It’s not only the most accurate test for colon cancer, it also prevents the disease

Colonoscopies are the best weapon against colon cancer, but nine out of 10 people who should have them don’t. That’s a mistake, says colon-rectal surgeon Linda Lapos, M.D., of Lehigh Valley Hospital and Health Network. “A colonoscopy not only finds cancer, it detects and removes growths in the colon before they become cancerous. That makes the second most common cancer very preventable.” Why isn’t everyone getting the test? Many are put off by the preparation a day or two before the procedure. You must go on a liquid diet and clean out your colon (large intestine) by taking laxatives in liquid and/or pill form. “The process is easier now because the pills are smaller and patients have more options,” Lapos says.

The procedure itself takes less than an hour. After giving you a mild anesthetic, your doctor inserts a thin flexible telescope (colonoscope) into your rectum and gently moves it through the 3 1/2 feet of your colon. Doctors look for mushroom-like growths called polyps, which they can remove during the colonoscopy. “It takes a polyp five to eight years to become cancerous, so regular screenings are important,” says Lapos’ colleague, gastroenterologist Carl D’Angelo, M.D.

When do you need a colonoscopy?

If you have a family history of colon cancer — your parent, sibling or child had the disease — start colonoscopies at age 40, or 10 years before the age when your family member was diagnosed.

If you have risk factors or symptoms of colon cancer, have the test right away. Besides family history, the main risk factor is chronic inflammation of the colon, or ulcerative colitis. Symptoms are changes in bowel movements or blood in the stool.

If you’re not in either of those categories, have your first colonoscopy at age 50. If you smoke or drink alcohol, talk to your doctor about starting screenings sooner.

“If no polyps are found, you won’t need another colonoscopy for about 10 years,” D’Angelo says. “If a polyp is found, you’ll need to be screened in about three years.” Talk to your doctor about your exact timing.

There are three other screening tools for colon cancer:

• Sigmoidoscopy involves less preparation and no anesthesia, but examines only part of the colon so polyps may be missed.
• Virtual colonoscopy uses a CT scan to examine the colon, but still requires colon-cleansing beforehand and isn’t as accurate as colonoscopy.
• Fecal occult tests examine a stool sample for blood. They’re the easiest tests, but the least accurate.

Want to Know More about colonoscopies, colon cancer or genetic testing and counseling? Read Ask Our Expert.

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