Evidence does not conclusively support widespread prostate cancer screening of healthy men for reduction of deaths in the long term, according to a systematic review of the literature.
In a move that could spark as much or more controversy as its recommendation against routine mammography for women in their 40s, the U.S. Preventive Services Task Force is taking this evidence and recommending against routine prostate-specific antigen (PSA) testing for healthy men in draft guidelines to be opened to public comment on Oct. 11.
Dr. Roger Chou and his colleagues conducted the review for the task force. They identified randomized trials of PSA-based screening, randomized trials, and cohort studies that compared prostatectomy or radiation therapy with watchful waiting, and large observational studies of perioperative adverse effects associated with surgical treatment.
"Screening based on PSA identifies additional prostate cancers, but most trials found no statistically significant effect on prostate cancer–specific mortality," the authors wrote. "Recent meta-analyses of randomized trials included in this review found no pooled effects of screening on prostate cancer–specific mortality."
In its 2008 recommendations, the task force previously had determined there was insufficient evidence for improved health outcomes (including reduced prostate cancer–specific and all-cause mortality) associated with prostate cancer screening for men younger than 75 years (Ann. Intern. Med. 2008;149:185-91). At the same time, they recommended against screening men 75 years or older, citing enough conclusive evidence to suggest the harms of screening and treatment would outweigh the potential benefits.
The current task force recommendations say no to PSA screening for all healthy men, regardless of age.
Dr. Chou and his colleagues noted the two largest, highest-quality studies in their review yielded conflicting results. The ERSPC (European Randomized Study of Screening for Prostate Cancer) randomly assessed 182,000 men aged 50-74 years to PSA testing or usual care (N. Engl. J. Med. 2009;360:1320-8). After a median 9 years, they found no statistically significant difference between groups in prostate cancer–specific mortality (relative risk, 0.85). A prespecified subgroup analysis did, however, show a 20% reduction in relative risk (0.80).
Investigators for the U.S. Prostate, Lung, Colorectal and Ovarian (PLCO) screening trial found no significant difference after 10 years in a study of 76,693 men ages 55 to 74 years randomized to PSA screening and digital rectal examinations vs. usual care (relative risk 1.1) (N. Engl. J. Med. 2009;360:1310-9).
"There is a substantial, cultural belief that prostate cancer screening saves lives. That does not reflect what the evidence shows."
"We think the task force reached a reasonable conclusion based on the evidence that they reviewed," said Dr. Len Lichtenfeld, deputy chief medical officer at the American Cancer Society, when asked to comment.
"What I think has to start happening is that doctors and their patients have to have a lot more honest conversations ... that this is not a test that has been shown unequivocally to have value when applied to large numbers of men, as it is being done today," Dr. Lichtenfeld said.
This call for more open and honest communication with patients about the relative risks and benefits of PSA testing is an essential feature of the society’s own 2010 recommendations on prostate cancer screening.
"At that time, we had looked at these same studies and we said we were unable to demonstrate conclusively that prostate cancer screening saves lives," Dr. Lichtenfeld said. "We weren’t advocating for or against [PSA test screening] but thought men needed to know that the evidence that this saves lives was limited and that the potential harms of diagnosis and treatment were real."
Public and physician perceptions, as well as the relative ease of ordering the PSA blood test, are real challenges to overcome, Dr. Lichtenfeld said. "There is a substantial, cultural belief – not only in the community but among health professionals – that prostate cancer screening saves lives. That does not reflect what the evidence shows."
"This is an easy test – it’s a blood test – go ahead and just do it. Why not?" he added. "Well, the ‘why nots’ are the men who are incontinent, the men who are impotent, the men who have radiation cystitis 15 years later [from resultant treatment] and are in so much pain that they can’t function."
The potential harms associated with false-positive tests and subsequent interventions are addressed in the systematic review. For example, about 1 in 200 men who undergo a prostate biopsy as a result of screening experiences a serious infection or urinary retention. The authors also noted that screening is likely to lead to overdiagnosis because the PSA enzyme test can pick up low-risk cancers that, left undetected and untreated, would not have caused death during a man’s lifetime.