November 2008: Volume 34, Number 11
Recommendations Revised for Colorectal Cancer Screening
Refining its previous recommendations, the U.S. Preventive Services Task Force (USPSTF) now says several methods are equally effective for colorectal cancer screening, and for the first time its recommendations also include an upper age limit for screening (Ann Intern Med 2008;149:627–637).
For adults age 50–75, the task force now recommends screening using annual high-sensitivity fecal occult blood testing (FOBT), flexible sigmoidoscopy every 5 years with fecal occult testing between exams, or colonoscopy every 5 years. Adults age 76–85 should not be routinely screened if they have had consistently negative screening test results since age 50, while all screening should stop after the age of 85 because the benefits of screening are too small compared to the risks. The task force previously recommended screening for all adults over age 50, but cited insufficient evidence to recommend one screening method over another or an age at which screening should stop.
In making the new recommendations, USPTF used an analysis from two colorectal cancer simulation models developed by the Cancer Intervention and Surveillance Modeling Network (CISNET). Based on assumptions about the natural history of colorectal cancer and the performance characteristics of each test, the models compared life-years gained relative to use of different strategies for screening in order to project expected outcomes of different screening strategies (See Graph below). This is the first set of recommendations based on simulation modeling, the task force noted. Previous recommendations have been based on clinical trial data.
The authors of the simulation study also pointed out that the simulation models did not consider newer screening tests such as computed tomography colonography or the DNA stool test, but only evaluated the screening strategies requested by USPSTF based on its 2002 review of evidence. The authors caution that their study assumed 100% adherence with screening, follow-up, and surveillance, while in practice adherence is much lower and varies among types of tests. The recommendations are available on the AHRQ website.