Colonoscopy screening is modestly effective for preventing colorectal cancer in patients aged 70 to 74, but the cancer prevention benefits may begin to diminish in older patients. The results of a prospective observational study are published in Annals of Internal Medicine.

Currently, no randomized, controlled trials of screening colonoscopy have been completed and ongoing trials exclude persons aged 75 or older. While screening guidelines from the U.S. Preventive Services Task Force recommend screening with any method, including colonoscopy, from age 50 to 75, Medicare reimburses colonoscopy with no upper age limit. Given that colonoscopy is invasive, expensive, and has potential for risks, it is important to understand the balance of benefits and harms in older patients.

Researchers reviewed a random sample of more than 1.3 million average-risk Medicare beneficiaries (2004 to 2012) aged 70 to 79 to evaluate the effectiveness and safety of colonoscopy to prevent colorectal cancer. Looking at data by age group (70 to 74 and 75 to 79), the researchers found that colonoscopy reduced the 8-year risk of colorectal cancer from approximately 2.6 percent to 2.2 percent in the younger group and from 3.0 percent to 2.8 percent in the older age group. The excess risk for serious adverse events after colonoscopy was small in both groups. Patients, physicians, and policymakers may want to consider these findings when making decisions about colorectal cancer screening, especially in upper age groups.