COMMENTARY

Prostate Cancer Screening Is Back in the News: Is the USPSTF Change a Good or Bad Idea?

Kenneth W. Lin, MD, MPH

Disclosures

April 17, 2017

Editorial Collaboration

Medscape &

This feature requires the newest version of Flash. You can download it here.

Hi, everyone. I'm Dr Kenny Lin. I am a family physician at Georgetown University Medical Center, and I blog atCommon Sense Family Doctor.

In a surprising reversal, the US Preventive Services Task Force (USPSTF), which since 2012 has discouraged prostate-specific antigen (PSA)-based screening for prostate cancer in men of any age, has posted new draft recommendations advocating that primary care clinicians routinely discuss the potential benefits and harms of screening in men aged 55-69 and screen men who desire the test. This new position is consistent with guidelines from the American Urological Association and the American Cancer Society. The American Academy of Family Physicians and the American College of Preventive Medicine currently recommend against PSA screening.

For the past 10 years, I have been personally invested in the PSA screening debate. As an employee of the Agency for Healthcare Research & Quality (AHRQ), which supports the activities of the Task Force, I was the lead author of the USPSTF's 2008 systematic evidence review[1] of PSA screening and a coauthor on their 2011 evidence review.[2] I left my position at AHRQ in part to protest the politically motivated cancellation of a Task Force meeting,[3] at which the recommendation against PSA screening was originally supposed to be discussed. And I have consistently argued that the harms of PSA screening outweigh its benefits in numerous lectures and articles. I was not involved in writing or reviewing the USPSTF's new evidence report, and I did not participate in the deliberations that led it to revise its previous recommendations.

Recent studies show that PSA screening rates have declined substantially in the United States over the past several years.[4] Family physicians who stopped screening or screen less often as a result of the Task Force's 2012 recommendations will want to know whether they should now reverse course. Are the estimates of benefits and harms of PSA screening that different from those we had 5 years ago? And are the new data enough to change practice?

The USPSTF's previous and current analyses were largely based on the results of two randomized trials of PSA screening: The European Randomized Study of Screening for Prostate Cancer (ERSPC)[5] and

The US Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial (PLCO).[6]

Both trials now have up to 15 years of follow-up, which is important because lead time means that any benefits of screening on prostate cancer mortality would take a decade or longer to occur. The ERSPC concluded that PSA screening modestly reduced prostate cancer deaths, but the PLCO did not. The positions of guideline groups on the usefulness of screening depends largely on which trial's results they rely on.

Both the ERSPC and the PLCO have limitations. Strictly speaking, the ERSPC is not one trial but seven. Seven study centers in different countries agreed to pool their data to increase the study's statistical power. In countries such as Sweden, PSA screening appeared to reduce prostate cancer mortality; in others, such as Finland, it made no difference. Another concern is that the screening group was more likely than control participants to receive curative treatment with radical prostatectomy,[7] even after adjusting for differences in cancer stages across groups, which could have exaggerated any benefits of the screening itself.

The major limitation of the PLCO is that it was conducted during a time when PSA screening was already occurring in the general US population, meaning that most of the "control" group received one or more PSA tests at some point during the trial. This effect would tend to dilute any true benefit of screening.

The USPSTF in 2012 judged that the ERSPC and PLCO trials, together, suggested that PSA screening may prevent a prostate cancer death in 0 to 1 man per 1000 men screened. On the harms side, 100-120 of these men will have at least one false-positive test result, and treatment of 110 additional men diagnosed with prostate cancer leads to 29 more men developing erectile dysfunction and 18 developing urinary incontinence.

This time around, the USPSTF gave considerably more weight to the ERSPC data. The Task Force now estimates that PSA screening prevents a prostate cancer death in 1 to 2 men per 1000 men screened, based on the trial's number-needed-to-invite-to-screening of 781. Harms of screening have not changed, except that fewer men with low-risk prostate cancer—the more indolent tumors most likely to be overdiagnosed—receive initial curative treatment, instead opting for active surveillance. But at least half of men who choose active surveillance eventually receive treatment, and during the surveillance period they are also exposed to the psychological effects of an untreated cancer diagnosis and the physical effects of yearly prostate biopsies.

I believe that the USPSTF's new draft recommendations paint too rosy a picture of the potential benefits of PSA screening and exaggerate the extent to which active surveillance reduces harms from treatment, when in fact it often only delays them while imposing other harms. The Task Force also did not account for the enormous opportunity cost of what is, at best, a marginally effective intervention. Eliciting patient preferences, explaining the complex PSA data, and true shared decision-making takes time—a lot of it—which crowds out time to discuss and provide more clearly effective preventive services in primary care.[8]

Screening selectively isn't a terrible idea, although I think the test does more harm than good overall. I still order PSA testing now and then for men who express a clear preference and understand what they're getting themselves into. But in changing the grade for PSA from "D" to "C," I fear that the USPSTF will inadvertently send the message that PSA screening can again become as commonplace as their other famous "C" recommendation: screening mammography in women younger than 50. And if that happens, it will undo the considerable progress family physicians have made in sparing older men the harms of this deeply flawed test.

This has been Dr Kenny Lin for Medscape Family Medicine. Thank you for listening.

Comments

3090D553-9492-4563-8681-AD288FA52ACE
Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.
Post as:

processing....