COLORECTAL CANCER SCREENING

The United States Preventive Services Task Force (USPSTF) has found convincing evidence that colorectal cancer screening substantially reduces disease-related mortality, but it does not recommend any one screening approach over another.

The final version of its colorectal screening recommendations was published online June 15 in JAMA. A draft that was open for comments was published last October.

The task force recommends that screening begin at age 50 years and continue until age 75 years. It highlights the fact that there is "convincing evidence" that colorectal cancer screening substantially reduces mortality and that not enough adults in the recommended age group are being screened.

The decision to continue screening past that age should be an individual one and should take into account the patient's overall health and prior screening history (C recommendation).

The USPSTF last issued guidelines for colorectal cancer screening in 2008. At that time, it recommended only three approaches to screening: colonoscopy, fecal occult blood testing (FOBT), or flexible sigmoidoscopy.

In the initial draft of their updated report that was released last October, these recommendations were largely unchanged.

The draft recommendations fell short of recommending CT colonography and multitargeted stool DNA (FIT-DNA), which the USPSTF said may be useful in "select clinical circumstance."

But in the final report, these two approaches have been added to the list, and the 2016 USPSTF recommendations now include seven different screening strategies: colonoscopy, fecal immunochemical testing (FIT) for occult blood, guaiac-based FOBT (gFOBT), sigmoidoscopy alone, sigmoidoscopy plus FIT, the FIT-DNA test, and CT colonography.

All of the screening strategies have varying levels of evidence supporting their effectiveness. Potential harms also differ among the specific approaches.

The USPSTF emphasizes that the evidence clearly shows that screening can reduce mortality from colorectal cancer, whichever strategy is used, and that not enough people are taking advantage of this.

"There are multiple screening options for colorectal cancer that reduce the risk of dying from the disease," commented former task force member Douglas K. Owens, MD, the Henry J. Kaiser, Jr, professor at Stanford University, in California.

"We encourage people to choose the best option for them, in consultation with their clinician," said Dr Owens in a statement.

Primary Goal Is to Increase Screening

In accompanying editorials, several experts weighed in on the recommendations.

The absence of a specific USPSTF recommendation for any one strategy does leave clinicians with a dilemma, comments John M. Inadomi, MD, from the University of Washington, in Seattle, in an editorial in JAMA Oncology.

"The highest-quality data exist for gFOBT, which has been replaced by FIT, and for sigmoidoscopy, which is largely unavailable [in the United States]," he writes. "Colonoscopy is the most often used screening test, and observational studies report reductions in cancer incidence and mortality, yet validation from randomized clinical trials is lacking."

Theoretically, FIT-DNA should be at least as effective as FIT, but there are no data to demonstrate greater reductions in cancer mortality beyond FIT, he notes.

Likewise, clinical outcome data are lacking for both radiographic and blood-based screening.

Cost may also play a role in the selection of a screening approach.

Although the USPSTF report does not address the economic effect of screening, the FIT-DNA test retails in the United States for $649 and is reimbursed by Medicare for $493, Dr Inadomi points out. In coparison, reimbursement for FIT is $22 and for colonoscopy, $773.

"For these reasons, FIT-DNA every 3 years is unlikely to represent a cost-effective alternative to screening with FIT or colonoscopy," he says.

It is in this context that the USPSTF has chosen not to make any specific test recommendations. Instead, it highlight the advantages and disadvantages of the strategies.

"Perhaps the absence of data should not indicate the absence of benefit, and these recommendations should be viewed as a living document that is expected to change as more information becomes available," he writes.

Of particular concern is that in the United States, adherence to colorectal cancer screening recommendations ranges from 58% to 65%. This rate has remained stagnant over the past 5 years.

The National Colorectal Cancer Roundtable has announced an ambitious effort to increase to 80% the proportion of the eligible US population who are up to date with screening by the year 2018. Dr Inadomi concludes that the focus should be on achieving this screening goal of 80% by 2018.

"While we may each have our own preference, this should be a patient-focused decision because the best test is not simply the one that gets done, but the one that gets done consistently," he writes.

Shared Decision Making

David F. Ransohoff, MD, of the University of North Carolina, Chapel Hill, and Harold C. Sox, MD, of the Patient-Centered Outcomes Research Institute, Washington, DC, concur with Dr Inadomi.

Writing in an editorial in JAMA, they note that the "USPSTF should be applauded for taking a global approach to a screening recommendation. The unique feature of the 2016 recommendations is that a goal — to increase screening rates — is driving the implementation strategy, which is to use shared decision making about an unusually broad range of screening options."

The point out that all stakeholders, including patients, physicians, health plans, and insurers, will want to know whether the USPSTF plans on using this strategy with respect to other aspects of screening.

"When the task force does recommend shared decision making, it would be helpful to develop a patient-friendly table that displays all of the evidence about all of the acceptable strategies," Dr. Ransohoff and Dr Sox write.