Positive margin length and gleason grade of tumor focus at the margin predict for biochemical failure after radical prostatectomy in patients with pT2 prostate cancer

INTRODUCTION AND OBJECTIVES: While 3 prospective trials have demonstrated benefit from adjuvant radiation (XRT) after radical prostatectomy (RP) in patients with positive surgical margins (PSM), its use varies amongst physicians. Many rely on clinical acumen to determine the optimal strategy for application of XRT post RP. We aim to determine if the length of PSM and highest Gleason grade (GG) of tumor at the PSM (hGGPSM) can be used to identify patients at greatest risk of biochemical failure (BCF) post RP. METHODS: A retrospective review of all RP patients at The University of Texas M.D. Anderson Cancer Center from 2002 to 2010 was performed. After a single pathologist review, patients with organ confined disease (pT2), pathologic N0/Nx and a PSM were included. A matched cohort of patients with pT2, pathologic N0/Nx and a negative surgical margin were identified for comparison. BCF was defined as 2 sequential PSA values of ≥0.2 or any detectable PSA prompting XRT. Patients receiving neoadjuvant hormone therapy, adjuvant XRT, or with <12 months follow-up were excluded. RESULTS: 205 patients with PSMs who met the inclusion criteria were matched with 205 control patients for comparison. Median PSA was 5.3 ng/mL (0.5-33) and median follow-up was 64 months (13-130). The majority were low clinical stage (cT1c: 65%), low (11%)/intermediate (82%) grade and had a single site of a PSM (90%). BCF occurred in 47 PSM patients in the PSM group vs 7 in the negative surgical margin group for a 5 yr BC failure free survival (BCFFS) of 69% and 96.8% respectively. PSM length was significantly associated with BCFFS (±1mm vs >1, p=0.02). When accounting for hGGPSM, Gl 3 tumors were less likely to experience BF (5 yr BCFFS-96%), while BCFFS for Gl >3 tumors were significantly different based on length of PSM (±1mm vs >1mm, p<0.0001). On multivariable analysis length of PSM (p=0.05) and hGGPSM (p=0.007) remained independent predictors of BCF (Table). CONCLUSIONS: Length of PSM and hGGPSM are independent predictors of BCF. These should be considered when evaluating patients for adjuvant XRT and in risk stratifying patients in prospective clinical trials. (Table Presented).