The controversy surrounding routine screening of PSA continues to burn. The ongoing debate was further fuelled by the draft recommendations issued by the US Preventive Services Task Force in October 2011.
Two experts on PSA communicate their opposing views on the USPSTF recommendations and offer evidence for and against routine PSA test. The point-counterpoint has been published in the March issue of Cancer Epidemiology, Biomarkers and Prevention.
In the United States, men over the age of 50 years undergo a simple blood test to detect the presence of prostate specific antigens (PSA). High levels of PSA are indicative of prostate health problems. However, recently, the USPSTF extended their recommendation against routine PSA screening of men over the age of 75 to include all men. It gave a ‘D’ rating to routine PSA screening in men above 75years, which means that there is absolutely no benefit from the test in this group of men and that the harms may outweigh the benefits. The task force based their decision on two large, randomized trials.
Richard J. Ablin, PhD. Dsc, Professor of Pathology, University of Arizona, Tucson, and discoverer of the prostate specific antigen (PSA) makes a point by supporting the USPSTF recommendations. He notes that, ‘controversy and debate of PSA screening were predictable from the onset and should have never in all actuality occurred, nor should have the tragedy of the resulting overdiagnosis and overtreatment in excess of a million men in the United States’.
William J. Catalona, MD, professor of Urology at Northwestern University Feinberg School of Medicine, Chicago, Illinois presents his counterpoint and says that, ‘the draft recommendation to downgrade PSA testing to a level ‘D’ is unfounded and irresponsible.
Point by Dr. Richard J. Ablin
Dr. Ablin in support of the recommendation says, ‘outcome of the studies on which the USPSTF evidence-based review and recommendation have been made will become quite understandable and acceptable by looking back at the ‘science’ on which PSA screening for prostate cancer has been based’. He notes that the enthusiasm over the idea of a blood test for presence or absence of prostate cancer, though the PSA was not cancer specific, initiated the use of PSA testing even prior to FDA approval.
Dr. Ablin writes that, the enthusiasm increased significantly with the results of an early landmark study. This was followed by ‘clever marketing of PSA test manufacturers,” along with the media, “through high-profile political, entertainment, and professional sports figures, and well intended but ill-informed urologists,’. The screening proliferation increased to ‘a fervor which would not disgrace a medieval inquisition’.
In 1994, the FDA approved the PSA test. Dr. Ablin says that ‘this was particularly puzzling’ because the PSA test is not cancer-specific and could not be used for cancer diagnosis. He writes, ‘Their evaluation was not based on a rigorous study of the specificity and sensitivity of the test’ and adds that FDA did not evaluate the risks and benefits associated with the test.
Dr Ablin identifies 4 fundamental cruxes: PSA is not cancer-specific, prostate cancer is an age-related disease, the PSA test cannot distinguish an indolent from an aggressive cancer, and there is no level of PSA diagnostic for prostate cancer.
The marginal decrease in prostate cancer mortality that was observed since the introduction of the PSA test can be attributed to improvements in surgical techniques, healthier patients with longer life expectancies, increase in awareness of prostate cancer and a general decrease in cancers of all types.
Dr. Ablin concludes by saying, ‘The Task Force recommendation will hopefully lead us to look at more fruitful endeavors toward identifying men who will benefit from early diagnosis and treatment for prostate cancer, wherein multiple groups, including myself, are actively pursuing new biomarkers’.
Counterpoint by Dr. William J. Catalona
Dr. Catalona presents his counterpoint and notes that the USPTF based their decision on three randomized clinical trials but did not weigh the results of two other trials that showed decrease in prostate cancer mortality. He writes, ‘The panel gave more weight to PLCO than to ERSPC, despite the fact that PLCO is more flawed, and they conclude that the mortality benefit from screening is ‘small to none’’.
Dr. Catalona strongly feels that the panel did not give due regard to epidemiological data on prostate cancer stage migration and mortality during the time PSA was being used. Dr. Catalona point out that, there was a 75% decrease in diagnosis of advanced prostate cancer and a 40% decrease in age-adjusted prostate cancer deaths in the US since the PSA routine test has been used. Other countries using PSA routine screening also show similar patterns of decreased mortality.
He feels that routine screening in men who fall into the high-risk group has not been studied adequately; however, these men have also been included in the USPSTF’s draft recommendation against PSA screening. He also points out that the task panel did not include any radiation oncologists, urologists, or medical oncologists. He adds that PSA screening as done in the randomized trials is not how it is conducted in clinical practice.
Dr. Catalona concludes by saying that the USPSTF recommendation has just managed to divide the medical fraternity and confuse the patients. He says that ‘nearly all urologists and most internists support PSA screening, but because of extensive media coverage, a change in clinical practice is likely and fewer patients will opt to be tested’.
Dr Catalona adds that, ‘PSA is the best screening test we have for the early diagnosis of prostate cancer, for now, no other way to identify prostate cancer in its curable stages exists’.
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