Dr. Tim Johnson: Colonoscopy Importance

Even though I wrote a column about colonoscopies only a month ago, I feel compelled to write about them again today because some very important new studies have been published recently.

In fact, I would call these new studies, reported in last week’s New England Journal of Medicine, the most important new medical information available in a very long time.

Put simply, these studies say that if you rely on a sigmoidoscopy — an examination that views about one-third of the colon — to detect early, possibly cancerous growths, you will miss up to half of those potentially lethal growths because they occur in the last two-thirds of the colon, which can be seen only by a colonoscopy.

So why have we relied so heavily on sigmoidoscopy as a screening exam for colon cancer?

Sigmoidoscopies Are Cheaper

If we are to be honest, we would have to say that it is largely for economic reasons. The sigmoidoscopy is a relatively easy exam and can be performed in a doctor’s office for relatively little cost.

In contrast, the colonoscopy — which looks at the entire colon — requires more skill on the part of the physician and light sedation for the patient, either in a hospital or an outpatient setting. The procedure is considerably more expensive and not as widely available.

Most current guidelines say that a colonoscopy should be used for screening only when early growths are first found during a sigmoidoscopy.

Sigmoidoscopies Miss Tumors

But the studies from last week prove what most of us have long suspected: If you rely on growths in the first one-third of the colon to alert you to growths in the rest of the colon, you will miss up to half of the growths that will likely go on to kill you.

It is no longer medically — or morally — correct to recommend the sigmoidoscopy as a screening exam. And if your doctor recommends a sigmoidoscopy instead of a colonoscopy, challenge him or her.

Availability of Colonoscopies

The political and medical establishment of this country must quickly figure out how to make colonoscopy more available, and more affordable. One possible way is to train special medical personnel to do the exam under the direction of a supervising physician, who would check any abnormalities found and remove any early growths.

A colonoscopy is the best way to detect early growths and prevent colon cancer, which is the second leading cancer killer in the country.

Theoretically, because it takes so long to get from the new growth stage to the lethal stage in colon cancer, we should be able to prevent nearly all deaths from the disease, providing we find the tumors early enough. All we need is the national commitment to make this happen.

ABCNEWS Medical Editor Dr. Timothy Johnson has provided commentary for viewers on ABCNEWS’ Good Morning America since the program’s debut in 1975. He also provides on-air analysis of medical news for World News Tonight, Nightline and 20/20. His column appears here every two weeks.