Clinical utility of percent-positive prostate biopsies in predicting biochemical outcome after radical prostatectomy or external-beam radiation therapy for patients with clinically localized prostate cancer.

Background and purpose: The clinical utility of the percentage of positive prostate biopsies in predicting prostate specific antigen (PSA) outcome after radical prostatectomy (RP) or external-beam radiation therapy (EBRT) for men with PSA-detected or palpable prostate cancer is not established.

Methods: A Cox regression multivariable analysis was used to determine whether percent-positive prostate biopsies provided clinically relevant information about PSA outcome after RP in 960 men, while accounting for the previously established risk groups based on the pretreatment PSA concentration biopsy Gleason score, and the 1992 American Joint Commission on Cancer clinical T stage.

Results: In the intermediate-risk group, 80% of the patients (stage T(2b) or biopsy Gleason 7 or PSA 10-20 ng/mL) could be classified into either an 11% or an 86% 4-year PSA control cohort using the preoperative prostate biopsy data. These findings were validated using an independent surgical (N = 823) and radiation (N = 473) data set. Percent-positive prostate biopsies added clinically significant information regarding time to PSA failure after RP.

Conclusions: The percentage of positive prostate biopsies should be considered in conjunction with the PSA level, biopsy Gleason score, and clinical T stage when counseling patients with newly diagnosed and clinically localized prostate cancer about PSA outcome after RP or EBRT.