Distribution and Associations of [-2]Proenzyme-Prostate Specific Antigen in Community Dwelling Black and White Men

Purpose: We provide cross-sectional normative data on [-2]proenzyme- prostate specific antigen from the Olmsted County Study of Urinary Symptoms and Health Status among Men, and the Flint Men's Health Study. We also describe associations with clinical urological measures and the risk of prostate cancer diagnosis. Materials and Methods: Measurements of [-2]proenzyme-prostate specific antigen were obtained from 420 white men from Olmsted County, Minnesota, and 328 black men from Genesee County, Michigan. Cross-sectional associations between [-2]proenzyme-prostate specific antigen and prostate enlargement/elevated prostate specific antigen were assessed. Cox proportional hazard models were used to assess associations between [-2]proenzyme-prostate specific antigen and the incident diagnosis of prostate cancer. Results: Baseline [-2]proenzyme-prostate specific antigen was slightly higher in black men at a median of 6.3 pg/ml (25th, 75th percentiles 4.1, 8.9) than in white men at a median of 5.6 pg/ml (25th, 75th percentiles 3.9, 7.7, respectively, p = 0.01). Baseline [-2]proenzyme-prostate specific antigen was highly predictive of biopsy confirmed prostate cancer in the Olmsted County Study cohort. Relative to men in the [-2]proenzyme-prostate specific antigen lower quartile those in the upper quartile were at almost eightfold increased risk for prostate cancer (HR 7.8, 95% CI 2.2-27.8) after adjusting for age and baseline prostate specific antigen. Conclusions: In these cohorts of community dwelling black and white men [-2]proenzyme-prostate specific antigen was much lower than in previous studies. These data suggest that [-2]proenzyme-prostate specific antigen may help identify prostate cancer in men with serum prostate specific antigen in an indeterminate range, although the reference ranges for white and black men may differ slightly.