PROSTATE-SPECIFIC ANTIGEN AS PREDICTOR OF PROSTATE-CANCER IN BLACK-MEN AND WHITE MEN

Background: The increasing incidence of prostate cancer creates comple x issues in health care management and cost containment. There is a ne ed to evaluate serial measurements of prostate-specific antigen (PSA) as a marker for long-term risk of clinically important prostate cancer (stages B through D). Purpose: We used a nested case-control design w ithin a retrospective cohort study to evaluate serial PSA concentratio ns in relation to subsequent prostate cancer diagnoses. Methods: Parti cipants included 40 black and 96 white men with subsequent diagnoses o f prostate cancer and 84 black and 100 white men without such diagnose s (control subjects) in a multiphasic health screening program conduct ed by the Kaiser Permanente Medical Care Program of Northern Californi a. Serial serum samples were collected 1.5-23 years before prostate ca ncer diagnosis. Results: Median serum PSA concentrations, specific for age and subsequent cancer status, were similar in blacks and whites. Concentrations in control subjects increased exponentially with age, w ith a doubling time of 24.9 years. Concentrations in men with stage A cancer were similar to those in control subjects. Until about 13 years before diagnosis, PSA in men with subsequent cancer stages B through D increased exponentially with age, with a doubling time similar to th at of control subjects. Thereafter, the PSA concentrations increased e xponentially, with a doubling time of 4.3 years, Rapid increase in PSA concentration started about 1.5 years earlier for men with stage D ca ncer than for men with stage B or C cancer. The single PSA measurement drawn closest to diagnosis was a more sensitive marker of stages B th rough D cancer within the next 7 years than was any index of change th at also took account of earlier PSA readings. Conclusions: These data suggest that 1) age-specific PSA concentrations are similar in black m en and white men and 2) current PSA concentration, specific for age, o utperforms changes in past concentrations in identifying the man who w ill develop stage B, C, or D cancer within 7 years, albeit at the cost of a slightly higher rate of false-positive results. This interpretat ion needs confirmation in other data containing many serial PSA measur ements within a few years of diagnosis.