Two major studies add fuel to fire of PSA controversy

Prostate-specific antigen testing, the most widely used screening tool in prostate cancer, has long had both critics and supporters. Two studies published in the New England Journal of Medicine continue to generate debate over the value of PSA screening. The papers have two major points in common: They are large-scale studies, and they leave more questions than answers.

In the first report from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, researchers found that after seven to 10 years of follow-up in almost 77,000 men (age 55 to 74), there was no benefit from routine PSA screening. The trial compared men who were encouraged to be screened regularly for PSA against a control group that received prevailing medical practices, or about a 50% rate of screening.

Between the two groups, differences in the rates of prostate cancer deaths were essentially statistically insignificant: In each group, roughly 200 deaths per million men occurred each year (N Engl J Med 360:1310-1319, 2009).

The European Randomized Study of Screening for Prostate Cancer was an interim look at seven European studies that together enrolled 162,243 men (age 55 to 69). The authors found modest benefit with PSA testing, but that benefit came at a cost: Saving one life from prostate cancer would require treatment of 48 men, according to the data. In other words, 47 men would be unnecessarily treated, and possibly suffer urinary incontinence or sexual problems, for every life saved (N Engl J Med 360:1320-1328, 2009).

Interpreting the results
In an accompanying NEJM editorial, Michael J. Barry, MD, from Boston’s Massachusetts General Hospital calls PSA testing “the controversy that refuses to die,” adding that there was hope that these study results would settle the controversy once and for all.

“After digesting these reports, where do we stand regarding the PSA controversy? Serial PSA screening has at best a modest effect on prostate cancer mortality during the first decade of follow-up. This benefit comes at the cost of substantial overdiagnosis and overtreatment. It is important to remember that the key question is not whether PSA screening is effective but whether it does more good than harm,” Dr. Barry wrote.

While Dr. Barry praised both groups of authors for managing such “monstrous trials,” he suggested that these ongoing results were released too early, as they do not offer a definitive set of findings (N Engl J Med 260:1351-1354, 2009).

Last year, the United States Preventive Services Task Force came out against screening for men 75 years and older (See “New task force guideline returns PSA screening to center stage,” November 2008). Given the conflicting opinions surrounding the value of PSA, physicians need to help their patients become fully informed about the potential benefits and harms involved in this screening tool. Oncology News International will continue to report on this issue and we encourage input from our readership.

Send your comments to: Ronald.Piana@cmpmedica.com.