Are PSA density and PSA density of the transition zone more accurate than PSA in predicting the pathological stage of clinically localized prostate cancer?

Abstract 

Purpose

To assess whether PSA density (PSAD) and PSA density of the transition zone (PSADTZ) are more accurate than PSA alone in predicting the pathological stage of prostate cancer.

Materials and Methods

One hundred and nine consecutive patients with clinically localized prostate cancer and preoperative PSA values over the whole range, treated with radical retropubic prostatectomy and limited pelvic lymph node dissection were included in this prospective study. Total prostate and transition zone volumes were measured by transrectal ultrasound using the prolate ellipsoid method. PSA, PSAD, and PSADTZ were compared to percentage of positive biopsy cores (% PC), biopsy and surgical Gleason score, and pathological stage, using univariate and multivariate analysis.

Results

Pathological stage was pT2a, pT2b, pT3a, and pT3b in 25.6%, 37.7%, 25.6%, and 11.1% of patients, respectively. Lymph node metastases were found in 4.6% of patients. PSA, PSAD, and PSADTZ were significantly related to % PC, biopsy, and surgical Gleason score and pathological stage (P < 0.001), and were equally able to predict higher pathological stage, i.e., seminal vesicle invasion and lymph node metastases. Only by adding % PC in multivariate analysis was it possible to discriminate intra- from extracapsular tumors.

Conclusions

The results of the present study demonstrate that PSAD and PSADTZ failed to outperform PSA in preoperative stage prediction of prostate cancer, possibly because the formula used to calculate them does not eliminate the contribution to total PSA of the nonmalignant portion of the gland.

Keywords: Prostate neoplasm, Neoplasm staging, Prostate-specific antigen, Transrectal ultrasound, Gleason score, Multivariate analysis