LETTER
Utility of the Prostate-specific Antigen Test
Steven H. Woolf, MD, MPH
15 June 1994 | Volume 120 Issue 12 | Pages 1053-1054
TO THE EDITOR:
The article by Kramer and colleagues was excellent, but I found the accompanying editorial inaccurate and misleading. Dr. Walsh argued that prostate screening tests are diagnostic because "75% of men older than 50 years have symptoms." He based this claim on his own book [1], in which he cited an estimate of the 40-year period prevalence for prostatic hypertrophy [2]. Period prevalence is an inappropriate measure of pretest probability. A more meaningful measure would be the point prevalence, which is about 3.5% for men older than 65 years [3]. The bias of a referral urology practice may account for the estimate that three of four men have prostate disease.
These and other arguments seemed tangential to the fundamental issue—that the health benefits of early detection and treatment are unproven. Nationwide screening would subject thousands of men with clinically insignificant disease to invasive procedures of uncertain benefit. To counter the data reviewed by Kramer and colleagues, Dr. Walsh offered a review article [4] as evidence that survival in selected case series reports was higher for radical prostatectomy than for expectant management. However, the authors of this review acknowledged that the analysis suffered from design flaws and warned against concluding that the "observed results were consequences of differences in the effectiveness of therapy."
More meaningful evidence will come from the clinical trial launched by the National Cancer Institute. Dr. Walsh made the disturbing suggestion that this trial, aimed at the fundamental question of effectiveness, should be postponed to do more research on PSA. If the same advice was followed for lung cancer, we would still be doing sputum cytology studies rather than the clinical trials that showed the ineffectiveness of cytology screening a decade ago [5]. Moreover, the National Cancer Institute trial design can change over time to accommodate his concerns. Given the current health care crisis, the examination of complex medical issues requires a more thoughtful and less biased analysis of fundamental principles.
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Author and Article Information
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Medical College of Virginia; Richmond, VA 23298
1. Walsh PC. Benign prostatic hyperplasia. In: Walsh PC, Retik AB, Stamey TA, Vaughan ED Jr, eds. Campbell's Urology. 6th ed. Philadelphia: W.B. Saunders; 1992:1009.
2. Glynn RJ, Campion EW, Bouchard GR, Silbert JE. The development of benign prostatic hyperplasia among volunteers in the normative aging study. Am J Epidemiol. 1985; 121:78.
3. Adams PF, Benson V. Current estimates from the National Health Interview Survey, 1991. Vital Health Stat 10(184). Hyattsville, MD: National Center for Health Statistics; 1991.
4. Adolfsson J, Steineck G, Whitmore WF Jr. Recent results of management of palpable clinically localized prostatic cancer: a review and commentary. Cancer. 1993; 72:310-22.
5. Fontana RS, Sanderson DR, Taylor WF, Woolner LB, Miller WE, Muhm JR, et al. Early lung cancer detection: results of the initial (prevalence) radiologic and cytologic screening in the Mayo Clinic study. Am Rev Respir Dis. 1984; 130:561-5.
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