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 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.
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.
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.
Clinical genitourinary cancer. 2016 May 29 [Epub ahead of print]
John M Watkins, Darrion L Mitchell, J Kyle Russo, Sarah L Mott, Chad R Tracy, Mark C Smith, John M Buatti
Department of Radiation Oncology, University of Iowa, Carver School of Medicine, Iowa City, IA. Electronic address: ., Department of Radiation Oncology, University of Iowa, Carver School of Medicine, Iowa City, IA., Bismarck Cancer Center, Bismarck, ND., Holden Comprehensive Cancer Center, Iowa City, IA., Department of Urology, University of Iowa, Carver School of Medicine, Iowa City, IA., Department of Radiation Oncology, University of Iowa, Carver School of Medicine, Iowa City, IA., Department of Radiation Oncology, University of Iowa, Carver School of Medicine, Iowa City, IA.