Prostate-specific antigen versus prostate-specific antigen density as predictor of tumor volume, margin status, pathologic stage, and biochemical recurrence of prostate cancer.

OBJECTIVES: To compare prostate-specific antigen (PSA) and PSA density (PSAD) calculated by transrectal ultrasound (TRUS) volume (TRUS PSAD), pathologic volume (Path PSAD), and weight (Weight PSAD) for their ability to predict pathologic characteristics and biochemical recurrence of prostate cancer. We also compared all PSAD derivatives to determine consistency.
METHODS: Between 1993 and 2002, 306 patients were retrospectively identified who had had PSAD determined preoperatively by TRUS and subsequently underwent radical prostatectomy with whole mounting and close step sectioning. The determination of stage, margin status, tumor number, individual tumor volume, and total tumor volume was obtained from the pathologic evaluation. Clinical follow-up was available for 265 patients.
RESULTS: The mean patient age was 62 years, the median Gleason score was 7, the median PSA level was 5.80 ng/mL, and the median TRUS PSAD was 0.16. The percentages of concordance for PSA, TRUS PSAD, Path PSAD, and Weight PSAD were similar in predicting margin status and extracapsular extension. Using linear regression analysis, PSA was more efficacious than TRUS PSAD, Path PSAD, or Weight PSAD in predicting the total tumor volume (R2 0.11, 0.08, 0.04, and 0.06, respectively). A significant positive correlation was found among TRUS PSAD, Path PSAD, and Weight PSAD. PSA was significantly better in predicting biochemical recurrence than TRUS, Path, or Weight PSAD (concordance 75.5%, 66.6%, 66.5%, and 70.4%, respectively).
CONCLUSIONS: PSA and TRUS PSAD are significant and equivalent predictors of margin status and extracapsular extension. A marked difference may exist between PSA and TRUS PSAD in predicting the total tumor volume and biochemical recurrence.