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.