Relationship between prostate specific antigen and indexes of prostate volume in Japanese men

Purpose: We determined the relationship between serum prostate specific antigen (PSA) and indexes of prostate volume in Japanese men, and compared that relationship with the one in white men. Materials and Methods: Data on a clinical cohort of 535 Japanese men with at least moderate lower urinary tract symptoms (LUTS) and clinical benign prostatic hyperplasia were examined. PSA, and total and transition zone prostate volume were related to age and linear regression analyses were performed to analyze the relationship between PSA and volume indexes. Results: The group of 535 men with a median age of 68 years had a median serum PSA of 1.5 ng/ml, and a median total and transition zone volume of 26.8 and 8.8 ml, respectively. PSA, total prostate volume and transition zone volume increased almost linearly with age. On univariate regression with age with each successive decade total prostate volume increased by 10.65% (95% CI 5.4 to 16.2), transition zone volume increased by 20.84% (95% CI 11.84 to 30.56) and the transition zone index increased by 3.1% (95% CI 1.66 to 4.57). On multivariate analysis the PSA-total prostate volume relationship was statistically independent of age. The study suggests that Japanese men might produce or release more PSA per unit prostate volume than white men. Conclusions: Japanese men with LUTS and clinical benign prostatic hyperplasia but no evidence of prostate cancer might produce and/or release more PSA per unit prostate volume than white men. To our knowledge the cutoffs for PSA and prostate volume to predict the response to LUTS therapy and the development of complications in Japanese men are unknown. Future studies in Japanese men are needed to identify these cutoffs.