Additional use of [-2] precursor prostate-specific antigen and "benign" PSA at diagnosis in screen-detected prostate cancer.

OBJECTIVES: To evaluate the adjuvant clinical use of [-2] precursor prostate-specific antigen ([-2]pPSA), which is associated with prostate cancer (PCa), and "benign" PSA, related to benign prostatic hyperplasia, in selecting a treatment strategy in patients with screen-detected PCa.
METHODS: Research-use immunoassays (Beckman Coulter) were used to measure [-2]pPSA, sum [-7, -5, -4, and -2]pPSA, and benign PSA from the frozen serum of participants from the screen arm of the European Randomized Study of Screening for Prostate Cancer, section Rotterdam, diagnosed with PCa with a serum PSA level lower than 15 ng/mL. We compared men with relatively benign PCa (Epstein's criteria; group 1) and men with arbitrarily defined aggressive PCa characteristics (Gleason score greater than 4 + 4 and more than four cores with PCa invasion or pT3C disease; group 2).
RESULTS: The data of 61 patients were evaluated. The median age in both groups was 68 years. Total PSA performed best in a univariate analysis, although in the multivariate analysis, the combination of pPSA and percent free PSA could correctly predict 95.5% of group 1 and 82.4% of group 2. The pPSA and percent free PSA forms remained statistically significant in the multivariate analysis of a subgroup of 30 participants normalized for PSA level and prostate volume; combined they correctly identified 89.5% and 54.5% of patients identified as having relatively favorable and aggressive PCa characteristics, respectively.
CONCLUSIONS: Adjuvant clinical use of pPSA over traditional parameters in selecting treatment strategies for men with PCa cannot yet be definitely determined. However, the promising results in a subgroup analysis warrant further investigation.