PREDICTIVE PROPERTIES OF SERUM PROSTATE-SPECIFIC ANTIGEN TESTING IN ACOMMUNITY-BASED SETTING

Background: Most studies that have described the sensitivity and speci ficity of prostate-specific antigen (PSA) as a screening test have bee n conducted in urology practice settings or in media-based screening p rograms. The control patients from these settings may have a higher pr evalence of urologic disorders that increase serum PSA levels than tha t of the general population in which screening efforts might take plac e, leading to biased estimates of sensitivity and specificity. Objecti ve: To determine the sensitivity and specificity of serum PSA levels f or the early detection of prostate cancer in a population-based settin g. Patients and Methods: This population-based case-control study was conducted in Olmsted County, Minnesota, where the Rochester Epidemiolo gy Project could identify all incident cases of prostate cancer throug h passive surveillance of medical care provided to local residents. Ca se patients were all 177 men (age range, 50-79 years) who were newly d iagnosed as having prostate cancer from 1990 through 1992 and had a pr ediagnostic serum PSA determination (90% of all incident cases). Contr ol patients were randomly selected from the Olmsted County population and had undergone a clinical examination to exclude prostate cancer. R esults: The median (25th and 75th percentiles) of serum PSA levels was 9.4 ng/mL (5.4 and 18.6 ng/mL, respectively) for case patients and 1. 2 ng/mL (0.7 and 2.1 ng/mL, respectively) for control patients (P<.001 ). When sensitivity was plotted against 1-specificity, the area under the receiver operating characteristic curve was 0.94 (SE, 0.01). The p redictive power declined somewhat with age. with areas under the curve of 0.96, 0.94, and 0.90 for men in their 50s, 60s, and 70s, respectiv ely. When cases were restricted to the 155 men with clinically localiz ed disease, the area under the curve was essentially unchanged (0.94; SE, 0.01) and still much greater than the estimates of 0.75 that were reported from urology practice- and media-based settings. Conclusions: In a community-based setting, serum PSA levels provide better discrim ination between men with and without clinically localized prostate can cer than has been observed in studies that were conducted in urologic practices. These results suggest that previous decision analyses may h ave underestimated the predictive value of PSA for the detection of pr ostate cancer in a primary care or community-wide screening program.