Task Force updates recommendations for colorectal cancer screening

The U.S. Preventive Services Task Force (USPSTF) issued an updated recommendation last week on screening for colorectal cancer in average-risk asymptomatic adults.

To update its 2008 recommendation on this topic, the USPSTF reviewed the evidence on the effectiveness of several available methods (including colonoscopy, flexible sigmoidoscopy, computed tomography colonography, the guaiac-based fecal occult blood test, the fecal immunochemical test, the multitargeted stool DNA test, and the methylated SEPT9DNA test) and screening strategies in reducing the incidence of and mortality from colorectal cancer or all-cause mortality. It also looked at evidence on possible harms of screening tests and their ability to detect adenomatous polyps, advanced adenomas based on size, or both, as well as colorectal cancer. The USPSTF recommendation statement was published online June 15 by JAMA.

The USPSTF noted convincing evidence that screening for colorectal cancer with several different methods can accurately detect early-stage colorectal cancer and adenomatous polyps. Although single test performance was an important issue, the sensitivity of the test over time is more important in an ongoing screening program, the Task Force stated.

The USPSTF also found convincing evidence that screening for colorectal cancer in adults ages 50 to 75 years reduces colorectal cancer mortality and recommended screening for this age group. The USPSTF found no head-to-head studies demonstrating that any of the screening strategies it considered are more effective than others, although the tests had varying levels of evidence supporting their effectiveness, as well as different strengths and limitations. No method of screening for colorectal cancer was shown to reduce all-cause mortality in any age group.

The benefit of early detection of and intervention for colorectal cancer declines after age 75, the USPSTF found. It noted that older adults who have been previously screened for colorectal cancer will enjoy at best a moderate benefit to continued screening from ages 76 to 85, but those in this age group who have never been screened are more likely to benefit than those who have. Therefore, the USPSTF recommended that the decision to screen for colorectal cancer in adults ages 76 to 85 years should be made on an individual basis, taking into account whether the patient is healthy enough to be treated if colorectal cancer is detected and any comorbid conditions that would significantly limit life expectancy.

In addition, the Task Force commissioned a microsimulation modeling study, also published online June 15, of a previously unscreened population undergoing colorectal cancer screening. The goal of the modeling study was to provide information on optimal starting and stopping ages and screening intervals across screening methods. The model, which assumed 100% adherence, concluded that the strategies of colonoscopy every 10 years, annual fecal immunochemical testing, sigmoidoscopy every 10 years with annual fecal immunochemical testing, and computed tomographic colonography every 5 years from ages 50 to 75 years provided similar life-years gained and a comparable balance of benefit and screening burden.

The USPSTF recommendation statement concluded that nearly 1 in 3 adults does not get screened for colorectal cancer. “For colorectal cancer screening programs to be successful in reducing mortality, they need to involve more than just the screening method in isolation,” the report stated. “Screening is a cascade of activities that must occur in concert, cohesively, and in an organized way for benefits to be realized, from the point of the initial screening examination (including related interventions or services that are required for successful administration of the screening test, such as bowel preparation or sedation with endoscopy) to the timely receipt of any necessary diagnostic follow-up and treatment.”

An accompanying editorial noted that the USPSTF appears to be saying that some tests are better than others but does not specify a preference. “How can tests differ and yet be the same in the eyes of the task force?” the editorial asks. “In the Recommendation Statement, the task force states a principle that may explain this paradox: ‘the best screening test is the one that gets performed.’ A test can rank low when tested on a representative population but still be better aligned with an individual patient's preferences and, therefore, be most likely to get done. Thus, to choose among the screening strategies, the USPSTF recommends shared decision making, a process in which physician and patient share information and reach a consensus about what screening test is best for the patient.”

Earlier this year, the Canadian Task Force on Preventive Health Care suggested colorectal cancer screening with a stool test every 2 years or sigmoidoscopy every decade among average-risk adults ages 50 to 74. Read more about comparisons and contrasts between guidelines in ACP Internist's June issue.