Performance of prostate-specific antigen mass in estimation of prostate volume in Japanese men with benign prostate hyperplasia

Does prostate-specific antigen (PSA) mass or free PSA mass improve the accuracy of predicting total prostate volume in relation to obesity in men with biopsy-proven benign prostatic hyperplasia?

We evaluated whether the prostate-specific antigen (PSA) mass or free PSA (fPSA) mass ( i.e ., absolute amount of total circulating PSA or fPSA protein, respectively), versus serum PSA or fPSA concentration, improves the accuracy of predicting the total prostate volume (TPV) in relation to obesity. Among men whose multicore (≥12) transrectal prostate biopsy was negative, 586 who had a PSA of ≤10 ng ml -1 and underwent the fPSA test prior to biopsy were enrolled. The PSA mass or fPSA mass (μ g) was calculated by multiplying the serum level by plasma volume. At each TPV cut-off point (30 ml, 40 ml, and 50 ml), the areas under the receiver operating characteristics curve (AUCs) of each variable were compared in obesity-based subgroups. AUCs of fPSA and fPSA mass for predicting TPV were significantly larger than those for PSA and PSA mass by 8.7%-12.1% at all cut-off points. Subgroup analyses based on obesity showed that, although PSA mass and fPSA mass enhanced accuracy by 4% ( P = 0.031) and 1.8% ( P = 0.003), respectively, for determining TPVs of ≥30 ml and ≥50 ml in obese and overweight men, they did not improve the accuracy in most other combinations of the degrees of obesity with TPV cut-off points. Thus, compared with serum PSA or fPSA, the absolute amount of PSA or fPSA protein mass improved the accuracy of predicting TPV in obese men very minimally and only for certain TPV cut-off points. Hence, these indicators may not provide clinically meaningful improvement in predicting TPV in obese men.

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 cm(3), 0.54; p-value of fPSA-fPSA mass for 40 cm(3), 0.34). fPSA performed significantly better than PSA at predicting prostate volume (p-value for 40 cm(3), <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.