SERUM-FREE PROSTATE-SPECIFIC ANTIGEN AND PROSTATE-SPECIFIC ANTIGEN DENSITY-MEASUREMENTS FOR PREDICTING CANCER IN MEN WITH PRIOR NEGATIVE PROSTATIC BIOPSIES

Purpose: We examined the usefulness of measurements of free prostate s pecific antigen (PSA) and PSA density for predicting prostate cancer i n men who had had a prior negative biopsy, a serum PSA level of 4.1 to 10.0 ng./ml. and benign findings on prostate examination. Materials a nd Methods: We measured percent free serum PSA and PSA density in 163 male volunteers age 50 years or older who were advised to have repeat prostatic biopsies for a serum PSA level of 4.1 to 10.0 ng./ml. Result s: Of 99 men who had repeat biopsies 20 (20%) had prostate cancer dete cted. Prostate cancer was significantly associated with lower free PSA level and higher PSA density, with overlap in 83% of the cases. The u se of percent free PSA cutoffs of 28 and 30% would have detected 90 an d 95% of cancers, respectively, and avoided 13 and 12% of the biopsies , respectively. PSA density cutoffs of 0.10 and 0.08 would have detect ed 90 and 95% of cancers, respectively, and avoided 31 and 12% of biop sies, respectively. Conclusions: Free PSA and PSA density predict pros tate cancer in men who have had prior negative prostatic biopsies, ser um PSA levels of 4.1 to 10.0 ng./ml. and a benign prostate examination . Both parameters may be used to avoid unnecessary biopsies with an ac ceptable decrease in sensitivity. Further studies are needed to determ ine cutoffs to be used in clinical practice.