After an all-clear, no-polyps screening colonoscopy, there is no need to undergo another one for at least ten years. This is the standard recommendation for all people over age 50 from organizations like the American Cancer Society. A new study, however, found a large portion of the Medicare enrollees with no sign of colon cancer on the screening colonoscopy are coming back too soon for another one. The perils of doing so include the risk of perforated colon, biopsy-related infection and other serious complications thought to occur more often in older people. That the repeat procedure is unnecessary means symptom-free elderly people are putting themselves at risk for no apparent benefit.

Virtually all colon cancer screening research concentrates on the underuse of colonoscopy, specifically by the uninsured and the minority populations who do not undergo screening colonoscopies in large numbers. The new study, led by James S. Goodwin, MD, and colleagues at the University of Texas, made the rare decision to look at overuse.

It is based on a random sample (5%) of over 24,000 Medicare beneficiaries whose records showed they had a negative screening colonoscopy. The Medicare claims database showed that a sizable minority underwent a repeat procedure prematurely. In people, aged 75 to 79 years, or 80 years or older at the time of the initial negative screening colonoscopy result, 47% and 33%, respectively, received a repeated examination within 7 years. This study was published recently in Archives of Internal Medicine as part of its excellent ongoing “Less is more” series.

Keep in mind that people over the age of 75 are underrepresented in screening studies so the risk of complications cannot be quantified with accuracy. This is part of the reason why the U.S. Preventive Services Task Force advises people to stop screening colonoscopy entirely at age 75 click here.

Dr. Goodwin and colleagues explained the implications of overuse: “First, screening colonoscopy can have adverse effects, including hospitalization and death. Too frequent performance of the examination may shift the benefit to risk ratio by increasing complications without additional benefit. Second, colonoscopy screening is costly; it is important to restrain expenditures for unnecessary procedures. Third, colonoscopy is a limited resource, in terms of facilities and practitioners. Identifying and decreasing overuse of screening colonoscopy should free up resources to increase appropriate colonoscopy in inadequately screened populations.”

In an e-mail message, Dr. Goodwin was asked to elaborate. “The point about screening is that you have to look at the effect on a population. If you harm more people in a population than you help, then screening is a bad idea. Almost all authorities think that to be the case with early repeat colonoscopies,” he wrote, in response.  “You also have to remember that the overwhelming majority of people are neither helped nor harmed. Since your lifetime chance of getting colon cancer is only about 5%, then for 95% of the population screening colonoscopies were unnecessary. It would be nice if we could identify that 5%, but we can’t. But we can certainly work harder to restrict colonoscopy to those who at least MIGHT benefit (i.e., not those with a normal one in past 10 years).”

Maryann Napoli, Center for Medical Consumers©

Related articles: “How accurate are colonoscopies?” and “Best way to screen for colon cancer?”  and this (apparently, you’re never too old or too debilitated for a screening test) “Screening right to the grave”.