Clinical utility of proPSA and “benign” PSA when percent free PSA is less than 15

To investigate the clinical utility of the subforms of free prostate-specific antigen (PSA), namely proPSA and “benign” PSA (BPSA), to improve cancer detection when the percent free PSA level is less than 15%. Percent free PSA, while maintaining sensitivity, has greatly improved the specificity of PSA for the early detection of prostate cancer. A low percent free PSA value indicates a greater risk of cancer, but only 30% to 50% of men with percent free PSA levels of less than 15% actually have cancer at biopsy. Archived sera from 161 consecutive men who were prospectively enrolled in our Early Detection Research Network prostate cancer early detection biomarker program with a percent free PSA value of less than 15% were included in the study. Total PSA, free PSA, proPSA, and BPSA were measured for each sample. The mean total PSA was 6.1 ng/mL (range 1.8 to 24.0). The mean age of the study group was 62 ± 7 years. Prostate cancer was detected in 66 (41%) of 161 men. The area under the curve-receiver operating characteristic for total and percent free PSA was 0.51 and 0.54, respectively. BPSA and proPSA/BPSA both improved cancer detection compared with percent free PSA alone; the improvement was statistically significant ( P