Positive surgical margin and oncological outcomes after robot‐assisted radical prostatectomy in different Cancer of the Prostate Risk Assessment risk groups

Objective To evaluate the impact of a positive surgical margin (PSM) in relation to the risk of biochemical recurrence (BCR) and additional treatment in different preoperative Cancer of the Prostate Risk Assessment (CAPRA) risk groups after robot‐assisted radical prostatectomy (RARP). Patients and methods Retrospective cohort study of 1039 patients subjected to RARP for prostate cancer at a single European institution. PSM was stratified by extent (focal extensive). The CAPRA score was used for risk group stratification. BCR was defined as a prostate‐specific antigen level >0.2 ng/mL. Additional treatment was defined as salvage radiotherapy (sRT) and/or androgen‐deprivation therapy (ADT). Results In total 227 patients had a PSM (21.8%). When compared to a negative surgical margin, an extensive PSM was associated with an increased risk of BCR (hazard ratio [HR] 2.16, 95% confidence interval [CI] 2.09–8.29; HR 3.76, 95% CI 2.33–6.06; HR 2.35, 95% CI 1.03–5.38) and sRT (HR 3.75, 95% CI 1.45–9.7; HR 4.57, 95% CI 2.47–8.43; HR 9.32, 95% CI 1.06–14.82) in the low‐, intermediate‐ and high‐risk groups, respectively. In high‐risk patients a focal PSM was associated with an increased risk of BCR (HR 5.79, 95% CI 1.62–20.65), sRT (HR 9.32, 95% CI 1.7–50.95) and ADT (HR 4.11, 95% CI 1.08–15.57) whereas in low‐ and intermediate‐risk patients a modest effect on BCR but no significant effect on sRT or ADT was found. We found no significant interaction between CAPRA risk group and PSM ( P = 0.25). Conclusions While an extensive PSM was associated with an increased risk of recurrence in all risk groups, a focal PSM was associated with additional treatment only among men with high‐risk tumours.