Prostate Cancer Study Affirms Value of PSA Test
Prostate Cancer and PSA Test
Refuting recent claims that the era of the prostate-specific antigen (PSA) test is over, physician-scientists at Columbia University Medical Center and NewYork-Presbyterian Hospital presented a study demonstrating that pre-operative PSA is an accurate measure of cancer recurrence. The study was presented today at the annual meeting of the American Urological Association (AUA) in San Antonio, Texas.
In a statistical analysis of 1,246 NewYork-Presbyterian/Columbia prostate cancer patients who underwent radical retropubic prostatectomy (RRP), removal of the prostate, with no adjuvant therapy between 1988 and 2003, investigators found that, when controlling for cancer stage and grade (Gleason sum and pathologic stage), pre-operative PSA is an accurate predictor of biochemical failure (BCF) (a measure of cancer recurrence defined as PSA≥0.2ng/ml), with the same degree of accuracy, irregardless of when the RRP was performed. This follows research presented at the 2004 AUA meeting by Dr. Thomas Stamey of Stanford University which found that PSA does not correlate with the amount of cancer that recurs following prostatectomy, but instead to prostate size, leading speculation about the continued predictive powers of PSA.
"Contrary to other recent interpretations, our analysis finds that PSA remains a vital tool for determining risk of recurrence in prostate cancer patients, indeed, the predictive ability of the PSA test does not significantly vary over the last 15 years," says Dr. Mitchell C. Benson, director of urologic oncology at NewYork-Presbyterian/Columbia and interim chairman of the department of urology and George F. Cahill Professor of Urology at Columbia University College of Physicians and Surgeons.
Investigators found that, when controlling for cancer stage and grade, there has been no significant change in the impact of PSA in predicting BCF. Researchers controlled for stage and grade because these two variables, with PSA, are used to predict outcome after surgery. Using a concordance index, the accuracy of PSA in predicting outcome, stratified by time period in which the procedure was performed, are statistically equivalent: .65 for the period 1988