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Colonoscopy debate doesn't negate need for tests

By: W. Gifford-Jones, MD / The Doctor Game

Posted: 06/1/2012 1:00 AM | Comments: 0

Tony Bock / The Canadian Press archives Many patients resist colonoscopies. (CP)

Is there any way you can avoid having a colonoscopy? A survey showed many believed the test isn't needed until symptoms occur. Others said their doctor never suggested one, or they were too embarrassed to discuss it. Still others said it was too painful.

If you're thinking this way, think again, because it may cost you your life.

But there is some good news about colonoscopy. A report from the University of California says it's time to stop offering this procedure as the only way to diagnose large bowel cancer. Instead, doctors should also be suggesting sigmidoscopy and the fecal occult blood test (FOBT). So why this change in thinking?

One prime reason is colonoscopy is always a hard sell. Patients don't like the bowel preparation, the strong laxative and drinking copious amounts of water. And many have heard of the discomfort. So why not inform the public of more patient-friendly methods and increase the number of cancers being detected?

But does this make sense? Dr. James Allison, professor emeritis of medicine at the University of California, San Francisco, an expert on colon rectal screening, says colonoscopy, which examines the entire large bowel, has never been proven as the gold standard compared to other tests.

For instance, Allison reports there is evidence a sigmoidoscopy done every five years is just as effective as a colonoscopy every 10 years. A sigmoidoscopy examines just the lower part of the large bowel, requires less bowel preparation and only minimal discomfort and is a much easier sell. Besides, the sigmoid is where most cancers occur. But the big negative is a sigmoidoscopy will miss cancers in the more distant parts of the colon. Two studies are currently in process to see if this thinking is correct.

The most patient-friendly test is the annual FOBT, used to detect hidden (occult) blood in stool samples. If the home kit detects blood, further tests, such as colonoscopy, must be done. The FOBT is still the standard test in many parts of the world as it's less expensive. One problem is false positive tests due to certain foods, medication or vitamin C. It also produces occasional false negatives that miss polyps or cancers that in the early stages do not bleed.

But is the colonoscopy always accurate? The test is not perfect and can miss up to four per cent of malignancies.

One problem is cancers in the sigmoid are usually raised polypoid growths that are easy to see and remove. Cancers and polyps in the distant part of the large bowel are often flat, which means they're not easy to spot. Doctors also can't diagnose what it's impossible to see. If patients fail to follow the proper routine of cleansing the bowel, fecal matter may hide the cancer from view.

The old saying "practise makes perfect" applies whether you're a mechanic or a doctor. Experienced physicians skilled in this procedure are more likely to detect cancerous lesions than less experienced colleagues.

So what to do? I remain convinced that the best way to avoid colon cancer is to have regular colonoscopies. Whatever way you cut the cake, malignancies can be missed if the entire colon is not examined.

For those who still refuse this procedure, a combination of sigmoidoscopy and FOBT should be done. Studies show that over the age of 50, one in three people develop a polyp that may become malignant. So the best policy is not to play Russian roulette. Have an annual FOBT done at the very least.

It's illogical to wait for symptoms of malignancy to appear as bleeding may not occur until a cancer is well advanced and has already spread beyond the bowel, with little chance of cure. Over the years, I've seen too many people leave this planet for using every excuse in the book for not submitting to colon-cancer screenings.

Remember the story of the camel who stuck his head in the sand. Not a good move for camels or humans.

See the website www.docgiff.com .

Republished from the Winnipeg Free Press print edition June 1, 2012 A25

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