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Is Earlier Colon Cancer Screening Wise?

On your 50th birthday, you'll get a present from your doctor -- a referral to colon cancer screening, preferably by colonoscopy.

But a new study suggests this gift might do more good if it arrives years earlier.

Most people don't get colon cancer before they're 60. Although colon cancer is deadly, it takes about a decade for colon polyps to turn into cancer (if they do -- most polyps never become cancers). Removal of polyps prevents colon cancer, so doctors start looking for polyps when a person turns 50.

Should doctors start looking earlier? A new study shows that people in their 40s are just as likely to have colon polyps as are people in their 50s. Study leader Alfred I. Neugut, MD, PhD, is acting chief of oncology at Columbia University Medical Center.

"Should we start screening people in their 40s? Maybe," Neugut tells WebMD. "It does take 10 years for a polyp to turn into cancer. So if people had screening in their 40s, maybe you would not see cancers in people in their 50s."

Neugut is quick to point out that this small study is by no means definitive. For one thing, there were too few patients. And the study did not evaluate whether the patients had family histories of colon cancer -- a risk factor for colon cancer that should trigger screening before age 50.

The study looked at colonoscopy results from 553 people aged 40 to 49 and from 352 people aged 50 to 59. All of these people received colonoscopies as part of a corporate health-screening plan.

The results:

  • 14 percent of 40-somethings and 16 percent of 50-somethings had one or more polyps.

  • 2 percent of 40-somethings and 3.7% of 50-somethings had a polyp that was becoming cancerous.

  • None of the 40-somethings and one of the 50-somethings had colon

"I see colon cancer patients, and I see a lot of 52- and 53-year-olds," Neugut says. "If we had caught their polyp when they were 47, I would not be talking to them when they were 52. I can't say that this study should lead to a change in screening policy, but we should consider it. Maybe we could compromise and say people should start screening at age 45."

Robert A. Smith, PhD, director of cancer screening for the American Cancer Society, doesn't think this is a good idea. He points out that since Neugut and colleagues did not know why their 40-something subjects agreed to colonoscopies, a significant number of them might have family histories of colon cancer.

Moreover, Smith says, if most of the people with polyps were in their late 40s, screening at age 50 would catch them before the polyps became cancers.

"And there is a rate of harm to colonoscopy," Smith tells WebMD. "If you start doing colonoscopies at younger ages, with less risk of colon cancer, you may be looking at a net harm instead of a net benefit."

Neugut says he isn't going to start advising colonoscopies for healthy 40-somethings without a family history of colon cancer.

"But if a healthy 45-year-old walked in the door and said, 'I want a colonoscopy,' I would not deter him," he says. "In the past, I might have tried to talk him out of it. So this study changes my practice to that degree."

Neugut and colleagues report their findings in the May issue of Gastroenterology.

By Daniel DeNoon
Reviewed by Louise Chang
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