Gleason Score ≤ 6 Prostate Cancer at Radical Prostatectomy: Does a High-Risk Setting Truly Exist? A Recursive Partitioning Analysis

Background: The purpose of this study was to determine whether a "high-risk" subpopulation of low-grade (Gleason score ≤6) prostate cancer defined by lower prostate-specific antigen (PSA) relapse-free survival (bRFS) might be identified within a large population of men who underwent radical prostatectomy (RP) alone, with mature follow-up.

Patients and methods: Patients were retrospectively identified for inclusion by cT1-2 prostate cancer managed with RP alone. Exclusion criteria were: Gleason score ≥7 at RP, any pre- or post-RP radiotherapy or hormone therapy, or PSA follow-up <12 months. The Kaplan-Meier method was used for survival estimates; recursive partitioning by conditional inference analysis was applied to identify variables associated with bRFS.

Results: From 2002 through 2010, 284 eligible patients were identified. Median age was 60 years (range, 44-76 years), 233 (82%) were cT1c, and median PSA was 5.3 ng/dL (92% ≤10). The median biopsy to RP interval was 50 days (range, 11-410, with 97% <180 days). Eighty patients (28%) had positive margin (M+). At a median follow-up of 92.6 months (range, 16.9-160.9, with 45% followed ≥ 8 years), 32 patients (11%) had PSA failure, with an estimated 8-year bRFS rate of 89%. In univariate analysis, M+, extraprostatic extension, detectable initial post-RP PSA, and longer biopsy to RP interval were significantly associated with lower bRFS. M+ and longer biopsy to RP interval remained significant in multivariable analysis. Recursive partitioning analysis identified M+ as the only stratification factor, with 8-year bRFS estimates of 74% versus 95% for M+ versus margin-negative.

Conclusion: Gleason score ≤6 prostate cancer managed using RP alone is associated with high rates of bRFS; however, margin positivity predicts early PSA failure rates in >20% of patients.