In 2012, the U.S. Preventive Services Task Force (USPSTF) recommended — amid much controversy — that men not be routinely given the PSA (prostate-specific antigen) blood test for prostate cancer screening. The test’s clear potential for harms outweighed its small potential for benefit, they said.
Earlier this week, the task force has updated that advice: The PSA test should still not be used routinely, they say, but physicians should discuss its harms and benefits with men aged 55 to 69. Each man can then “incorporate his values and preferences into his decision” about whether or not he wants to be screened.
The panel still recommends against PSA-screening for men aged 70 or older.
The draft recommendations (they will not be finalized until later in the year) apply to adult men at average or increased risk for prostate cancer who have not been diagnosed with the disease and have no signs or symptoms.
‘A wrong impression’
In the days since that update was published, some media headlines have made it seem as if the USPSTF has “changed its mind” or is now “OK” with PSA-screening. But, as Kathlyn Stone, an associate editor with the Minnesota-based HealthNewsReview points out, “that would be the wrong impression.” Here’s why:
What the revised guideline does is make a slight change. It changes the recommendation for routine prostate cancer screening from a “D” (which discourages the service since “There is moderate or high certainty that the service has no net benefit or that the harms outweigh the benefits.”) to a “C (which means that physicians should “Offer or provide this service for selected patients depending on individual circumstances,” and that “There is at least moderate certainty that the net benefit is small.”)
“The main point,” adds Stone, “is that men who are candidates for testing (ages 55 to 69) should discuss the benefits and harms of the test with their doctors and make a personal decision about whether to take it.”
‘Hardly a ringing endorsement’
Dr. Vinay Prasad, an oncologist at Oregon Health and Science University, agrees. “The new guidelines should hardly be construed as a ringing endorsement,” he writes in a commentary for STAT. “PSA screening remains a difficult decision for healthy men and their doctors.”
“Prostate cancer screening may be OK for some men — those who are more tolerant of risk and uncertainty — but it is surely not right for others,” he explains. “As for African-American men, or men with a family history, the USPSTF provides caution that there is no good evidence to show greater benefit from the test, and it is possible the harms are greater in these groups.”
The potential harms are numerous: “False positives, overdiagnosis — which means treating a cancer that would otherwise not cause harm — and the side effects of diagnosis and treatment, including incontinence, impotence, and even death,” says Prasad.
“In my mind, the greatest misconception about the test is that we say it ‘saves lives’ when that is uncertain,” he adds. “PSA testing reduces the risk of dying of prostate cancer, but there is no evidence it reduces the risk of dying.”
Understanding all options
As Dr. Otis Brawley, chief medical and scientific officer with the American Cancer Society, points out in a commentary for CNN, “it is fair to say the harms of prostate screening are better proven than the benefits, although benefits likely do exist.”
“One proven harm is overdiagnosis,” he notes. “Some cancers, ironically the ones easiest to diagnose and cure, are so slow-growing they are of no threat to the patient: They do not need to be cured, as they would never do harm if left alone. One epidemiologic study suggests that more than 1 million American men received unnecessary treatment over the past 25 years.”
Brawley applauds the idea of shared patient-doctor decision-making regarding PSA screening. “Good scientific research has bought about improved understanding of cancer and the limitations of screening tests, diagnostics and treatment,” he says. “This is leading more and more to professional guidelines that respect patient preference and put the screening decision in the hands of the patient.”
Brawley also hopes, however, that men diagnosed with prostate cancer are not rushed into treatment, but given a chance to “explore and consider all reasonable options.”
“Recent studies of health practices show a movement away from immediate aggressive therapy for all prostate cancers and increasing use of ‘active surveillance’ or monitoring when PSA testing finds a low-risk cancer,” he points out. “That means fewer harms from surgery and radiation.”
A key factor
The greater acceptance of active surveillance as a treatment strategy seems to have been a key factor behind the USPSTF’s updated recommendation.
“In 2012, we were … very concerned about the harms [of screening] and the harms of overtreatment,” said the chair of the task force, Dr. Kirstin Bibbins-Domingo of the University of California, San Francisco, in an interview with Clinical Oncology News. “There are now strategies that can help some men mitigate the harms that may be associated along the way with prostate cancer screening and treatment.”
In addition, she said, active surveillance “appears to be effective; it is gaining increased use in the U.S., from 10% to now 40% among low-risk men, and this strategy means that some men with low-risk prostate cancer can avoid treatment altogether, and other men at least will be able to delay treatment.”
But, as Prasad cautions in his STAT commentary, “PSA screening is OK only if doctors are honest about what the test can and cannot do.”
“For some men, the benefit and uncertainty might be worth it,” he adds. “But for others it may seem like so much for so little.”
FMI: You can read the USPSTF’s report on its updated recommendations on the panel’s website. The draft recommendations are open for public comment through May 8.