Colonoscopy is one of the most effective cancer screening procedures available. Colon cancer grows very slowly and can be treated if caught early through screening. But, perhaps because of this success, older Americans are undergoing screening colonoscopies despite recommendations against screening in adults aged 76 and older.

A new study by researchers at the University of Texas Medical Branch at Galveston published online today in JAMA Internal Medicine shows that one out of four colonoscopies paid for by Medicare is potentially inappropriate under current screening guidelines set forth by the United States Preventive Services Task Force.

A screening procedure for cancer, as opposed to a diagnostic one, is done at certain recommended ages and intervals to find early cancers before symptoms emerge. The Pap smear, the mammogram and the PSA test are examples. A diagnostic test, on the other hand, is done when a patient experiences symptoms that indicate an abnormality such as bleeding, pain or a lump.

The USPSTF says a colonoscopy is inappropriate if repeated within 10 years after a negative screening result in a patient 70 to 75 who is not experiencing symptoms. Routine screening colonoscopy is not recommended for patients 76 to 85 years, and any screening at all is discouraged in patients older than 85.

The UTMB researchers looked at claims data on all Medicare patients in Texas 70 and older who had colonoscopies during a one-year period between 2008 and 2009. The researchers also looked at data on five percent of the 70 and older Medicare patients throughout the United States who had colonoscopies during that same time period. The researchers found that 23.4 percent of colonoscopies paid for by Medicare were potentially inappropriate, based on USPSTF guidelines.

“Screening colonoscopy comes with a real risk of complications for older adults, such as perforation, bleeding or incontinence,” said lead researcher Kristin Sheffield, assistant professor of surgery at UTMB.

The researchers are not saying that patients who have symptoms such as anemia, gastrointestinal bleeding or abdominal pain should forgo colonoscopies. In fact, they insist that patients with relevant diagnoses should receive further testing. “At the same time, however, older adults are less likely to benefit from early detection because the natural history of colon cancer usually involves a slow progression from polyp to cancer,” said Sheffield.

The other authors on the study include Yimei Han, Yong-Fang Kuo, Dr. Taylor Riall, and Dr. James Goodwin.

The research was supported by a grant from Comparative Effectiveness Research on Cancer in Texas, Cancer Prevention and Research Institute of Texas and the National Institutes of Health.

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The University of Texas Medical Branch