PSA SCREENING DEBATE CONTINUES

July 16, 2012 ( UPDATED July 17, 2012 ) — Screening asymptomatic men for prostate cancer with the prostate-specific antigen (PSA) test is worth doing, according to the American Society of Clinical Oncology (ASCO).

In contrast to the blanket statement issued by the United States Preventive Services Task Force (USPSTF), which did not recommend routine PSA testing for any asymptomatic man, regardless of age, the new guidance issued by ASCO is more nuanced. It concludes that PSA testing can be recommended for asymptomatic men with a life expectancy of more than 10 years, but not less.

However, the new guidance, published online today as a provisional clinical opinion in the Journal of Clinical Oncology, stops short of actually recommending PSA testing for asymptomatic men with a life expectancy of more than 10 years.

Instead, it recommends that physicians and such men "discuss" whether PSA testing is appropriate. ASCO has published a decision aid to facilitate these discussions.

Should Not Be Discounted

"Our critical review of the evidence, including data on younger subpopulations of men, shows that PSA testing should not be discounted," said Robert Nam, MD, a uro-oncologist at the Odette Cancer Centre, Sunnybrook Health Science Centre, University of Toronto, in Ontario, and cochair of the ASCO panel.

"We recognize that many want this debate settled, and want the answer to be clear-cut," he said. "But it isn't."

"Until it is, we think physicians and men with longer life expectancies should be aware of the full scope of evidence on PSA testing for prostate cancer screening so they can make informed and shared decisions about the right course of action," Dr. Nam said in a statement issued by ASCO.

In what is bound to raise some hackles at the American Urology Association, the statement describes ASCO as "the organization representing physicians who counsel and treat men with prostate cancer."

"We see the impact of screening and treatment decisions every day, and felt it was our responsibility to conduct a rigorous analysis of the available data to help guide this very important decision for many men," explained the other cochair of the expert panel, Ethan Basch, MD, a medical oncologist specializing in prostate cancer at the Memorial Sloan-Kettering Cancer Center New York City.

"Our approach is a balanced one that takes into consideration the life expectancy of the patient, as well as the values and preferences of the individual," he said. "We also advocate for the use of evidence-based decision aids, research to improve screening methods, and reduction of overtreatment of likely insignificant cancers."

Same Data, Different Conclusions

The ASCO panel of experts and the USPSTF used the same body of evidence — a review carried out the Agency for Healthcare Research and Quality. However, they came to different conclusions.

"For men with a shorter life expectancy, we agree that the risk of harms associated with PSA-based screening and subsequent unnecessary treatment likely outweigh the benefits," Dr. Basch explained.

"But for men with a longer life expectancy, our assessment of the evidence shows the balance of risks and benefits is less clear, and that well-informed conversations between men and their physicians remain worthwhile about harms, potential benefits, and appropriate management strategies if prostate cancer is found," he noted.

Although ASCO used the same basic dataset, its panel of experts "considered updated, longer-term data from clinical trials, gave greater consideration to data in a subpopulation of younger men, and weighed the impact of that analysis differently than the USPSTF." As a result, the ASCO panel of experts concluded that PSA testing might reduce the risk for death from prostate cancer in men with longer life expectancies.

The ASCO panel explains that although "large clinical trials have found no reduction in overall mortality from routine PSA-based screening, the evidence is less clear in healthy men with life expectancies over 10 years, [and] this subpopulation alone may have lower prostate cancer specific-mortality with PSA testing."

In particular, they highlight the updated results from the European Randomized Study of Screening for Prostate Cancer (ERSPC). Data from the 11-year follow-up of this trial, published earlier this year (N Engl J Med. 2012;366:981-990), showed that PSA testing reduced death rates from prostate cancer by approximately 20% in a subpopulation of more than 162,000 men 55 to 69 years of age.

When the updated results were published, Gerald Chodak, MD, from Weiss Memorial Hospital in Chicago, Illinois, said, in his Chodak on Urology videoblog, that "after more extensive surveillance, the [mortality rate] might have shifted to a much more favorable number." He concluded that "at the end of the day, each patient needs to decide what odds of benefit he is willing to accept and the potential side effects that go along with treatment."

"As doctors, we need to inform our patients and then let them make a decision," Dr. Chodak added.

The ASCO panel hopes that these discussions will be helped by the decision tool it has devised to help with this patient–physician interaction.

Decision Aid

The decision aid is a booklet aimed at an individual who is deciding whether or not to have the PSA test. It outlines in great detail the risk and benefits of having the test, and depicts the odds in pictograms. All of figures are taken from the updated results of the ERSPC.

Each pictogram looks like a sheet of graph paper, with 1000 tiny boxes; several of these are colored to show the odds of an event. For example, the first pictogram illustrates the odds of dying from prostate cancer with and without PSA testing. For those tested, 4 boxes are colored, indicating that there were 4 deaths from prostate cancer per 1000 men; for those not tested, 5 boxes are colored.

A section on "weighing your options" summarizes the potential benefits and risks, and requires the respondent to score 2 questions (from 0 to 5) about each of 30 factors — How much does this matter to you, and how likely is this to happen to you?

The 10-page booklet also lists a variety of other sources on PSA testing for men who want more information, including several other decision-aid tools.

The new decision tool requires quite a bit of input from the individual and could be a time-consuming undertaking. As stated in the introduction: "The decision to get a PSA test is not a simple one."

Reaction to the New Publications

Asked for a reaction to the new publications, Edward Messing, MD, chairman of urology and professor of oncology and pathology at the University of Rochester School of Medicine and Dentistry in New York, said the new guidance was "reasonable," but the new decision aid was "not practicable."

In an interview with Medscape Medical News, Dr. Messing said that the new ASCO recommendation to discuss the PSA test with men who have a life expectancy of longer than 10 years is "very reasonable" and is "far more reasonable" than the blanket statement from the USPSTF against all routine use of test in asymptomatic men.

However, he was rather bemused by the decision aid and said that it was "unequivocally a consensus document," adding that although it was correct, it gave too much information and ended up distorting the issue. "It is not practicable for an average man who has no prostate symptoms," he said. Such a man needs to decide whether or not to take the test, he said, and the crux of this is represented in that very first graphic representation, showing that 4 men in 1000 who are tested die from prostate cancer compared with 5 men in 1000 who are not tested.

All of rest of it could lead to information overload, he suggested. Dr. Messing said it took him a full 15 minutes to read through the 10-page booklet, and he joked that the graphic representation of the data and the dense information summaries "would be satisfactory only to an engineer." Even the brightest of men would find it difficult to wade through the whole booklet, he said.

J Clin Oncol. Published online July 16, 2012. Abstract