Prostate-specific antigen mass and free prostate-specific antigen mass for predicting the prostate volume of Korean men with biopsy-proven benign prostatic hyperplasia

Purpose: It has been reported that prostate-specific antigen (PSA) correlates with prostate volume. Recently, some studies have reported that PSA mass (PSA adjusted for plasma volume) is more accurate than PSA at predicting prostate volume. In this study, we analyzed the accuracy of PSA and the related parameters of PSA mass, free PSA (FPSA), and FPSA mass in predicting prostate volume. Materials and Methods: We retrospectively investigated 658 patients who underwent prostate biopsy from 2006 to 2012 and had a confirmed negative biopsy result. International Prostate Symptom Score (IPSS) questionnaire, PSA, FPSA, and prostate volume were investigated. PSA mass and FPSA mass were calculated by use of established formulas. The association between PSA-related parameters and IPSS and prostate volume was assessed by using Pearson correlation coefficient and receiver operating characteristic curves. Results: There was no significant difference between PSA and PSA mass, FPSA, or FPSA mass in predicting prostate volume except in obese patients (p-value of PSA-PSA mass for 40 cm³, 0.54; p-value of FPSA-FPSA mass for 40 cm³, 0.34). FPSA performed significantly better than PSA at predicting prostate volume (p-value for 40 cm³, <0.001). IPSS and the aforementioned PSA-related parameters were not significantly correlated. Conclusions: PSA mass was not a better predictive value than PSA for estimating the prostate volume in Korean men except in obese men. This finding was also applicable to the relationship of FPSA and FPSA mass, which appeared to be more accurate predictors of prostate volume than either PSA or PSA mass.