December 29, 2011
Prostate Cancer Screening Deserves a Passing Grade
BY Scott Merville
A federal task force that gave prostate cancer screening a D grade -- as in don't screen men who have no symptoms of the disease -- should bump that rating to a C, an MD Anderson scientist argues this week in a commentary in the Journal of the American Medical Association.
A grade C more closely fits available clinical evidence and will encourage clinicians to engage men in informed decision-making, a process that the D grade is likely to preempt, Robert Volk, Ph.D., professor in General Internal Medicine, notes with co-author Andrew Wolf, M.D., of the University of Virginia.
The USPSTF reviews evidence from clinical research and then recommends a variety of grades for a service, ranging from A (recommended, with a high certainty that the net benefit is substantial) to D (recommends against the service because there is moderate or high certainty that the service has no net benefit or that the harms outweigh the benefits.)
Prostate cancer screening by testing for levels of the prostate-specific antigen currently has an I grade -- the current evidence is insufficient to assess the balance of benefits and harms of the service.
Based on trial results
Volk and Wolf note that the task force relied on the results of three randomized screening trials, which it rated as being of fair quality. Two of those three show a benefit of screening. The European Randomized Study of Screening for Prostate Cancer found that 1,410 men must be screened an average of 1.7 times over nine years to prevent one prostate cancer death. This is comparable to the benefit of mammography for women ages 50-59, the author's note, which the USPSTF has recommended for a B grade.
The Goteborg trial, a Swedish subgroup of the European study, found that only 293 men would need to be screened to save one life from prostate cancer. However, the task force found this group's differing results from the larger trial raises doubts about their validity.
"Regardless of the controversy surrounding the question of benefit, there is unanimity in the estimation of harm," Volk and Wolf write. "All agree that men face serious risks from diagnostic testing and treatment of screen-detected prostate cancers ranging from sexual, urinary, and bowel injury to treatment-related death. Moreover, many men who are diagnosed with and treated for prostate cancer have cancers that were never destined to harm them, illustrating the thorny problems of over diagnosis and over treatment."
"The crux of the prostate controversy," Volk and Wolf continue, "is that many men place such a high value on averting death from cancer that they are willing to undergo risk and harm to achieve that goal. Many other men are not."
Clinicians can reconcile this difference by "engaging men in informed decision making." The task force's own recommendation is consistent with this approach and is nearly identical to those of organizations such as the American Cancer Society, the authors note.
The USPSTF recommends that men who are being considered for screening:
Participate in an informed decision, preferably with their physician
That they not be tested without their consent
And that community-based screening without informed consent should be discontinued.
Patient choice not accounted for The task force doesn't address the use of patient decision aids -- publications, videos, interactive internet applications -- that promote better health care decision making. Volk and colleagues developed an interactive decision aid for newly diagnosed prostate cancer patients that has been adopted by the U.S. Agency for Healthcare Research and Quality.
A C grade would better fit the USPSTF recommendation because it still opposes routine screening, but also notes "there may be considerations that support providing the service in an individual patient. There is at least moderate certainty that the net benefit will be small."
A C encourages thoughtful discussion, while a D preempts it, the authors note. "The fundamental difference is that a C recommendation allows for individualized decision making, such that men can be apprised for the potential benefits and harms of screening and decide in partnership with their physician whether to proceed."
The USPSTF D grade recommendation was made in October, a public comment period ended on Dec. 13.
Resources: JAMA: Grading the New US Preventive Services Task Force Prostate Cancer Screening Recommendation (Volk & Wolf)
JAMA: Prostate Cancer Screening--Time to Abandon One-Size-Fits-All Approach? (Kim & Davis)
USPSTF: Screening for Prostate Cancer