Prostate specific antigen and prostate specific antigen density. Roles in patient evaluation and management.

Prostate specific antigen (PSA) is the most accurate serum marker for prostate cancer. However, sensitivity and specificity are suboptimal, especially at the intermediate levels between 4.1 and 10.0 ng/ml (monoclonal). For intermediate PSA levels, PSA density (PSAD) provides unique information regarding the need for biopsy and the likelihood of prostate cancer. The authors prospectively used PSAD to determine the need for biopsy in 68 patients with PSAD values below 0.150 and normal results from a digital rectal examination. Ten patients have undergone biopsy secondary to a rising serum PSA. Three were found to harbor prostate cancer and have undergone therapy. The remaining 65 patients continue on surveillance. PSAD can predict treatment outcomes for patients with clinically localized prostate cancer treated with radical prostatectomy. PSADs at low values are 90% accurate in predicting operative success. PSADs at high values are 67% accurate in predicting failure. Cancer 1994; 74: 1667-73.