Extensive PSA Screening Unwarranted?

Dependence on serum levels of prostate specific antigen (PSA) as a marker of cancer has led to overly zealous treatment of men with prostate hyperplasia, investigators at Stanford University report.

However, they believe that the PSA test “will remain an enduring marker for both benign prostatic hypertrophy and its rate of progression.” The test will also “continue to be useful also as a marker of failure to cure the patient after radical prostatectomy and probably irradiation of the prostate as well.””What we didn’t know in the early years is that benign growth of the prostate is the most common cause of a PSA level between 1 and 10 ng/mL,” lead author Dr. Thomas A. Stamey notes in a university press release. Dr. Stamey first reported in 1987 that PSA levels could be used as a marker of prostate cancer.However, evidence that PSA testing is not very sensitive has been accumulating. Finding out why this is so was the basis for the California-based team’s current research, outlined in the Journal of Urology for October. Dr. Stamey’s group examined tissue from the 1317 radical prostatectomies performed at Stanford since 1983 to quantitate all histologic aspects of the cancers. They compared the findings with the patients’ serum PSA levels and other preoperative characteristics.During the first 5-year period, 90.79% of cancers were palpable on digital rectal examination (DRE), average volume of the largest cancer was 5.33 cc, and mean capsular penetration was 1.54 cm. Between 1999 and 2003, these values had declined to 16.76%, 2.44 cc and 0.22 cm, respectively. Mean serum PSA levels had declined from 24.74 to 8.14 ng/mL.While six histologic morphologic features were significantly associated with serum PSA between 1983 and 1988, by the last 5-year period, the only trait related to serum PSA was prostate weight.What has happened, Dr. Stamey’s group suggests, is that prostate cancer is being over-treated, given that most men will develop the disease if they live long enough and the low associated mortality rate. Thus, the authors conclude, the current extensive use of PSA screening is unwarranted. Until a better serum marker for prostate cancer is found, “we should emphasize better training in careful palpation of the prostate, especially with the patient in the ‘knee-chest’ position on the examining table.””Palpable cancers… almost always require some form of treatment,” they add.(Source: J Urol: Reuters Health News: Oncolink: September 2004.)