Evaluation of positive surgical margins in patients undergoing robot-assisted and open radical prostatectomy according to preoperative risk groups

Objectives: Recent studies showed that robot-assisted radical prostatectomy (RARP) represents an oncologically safe procedure in patients with prostate cancer (PCa), where the rate of positive surgical margins (PSMs) might be lower in patients treated with RARP as compared with that of those undergoing the open approach (open RP [ORP]). The aim of this study is to analyze the rate of PSMs according to preoperative risk groups in a large cohort of patients treated with RARP and ORP in a single institution with standardized surgical technique and pathological examination.

Materials and methods: We evaluated 6,194 consecutive patients with PCa undergoing either ORP (71.1%) or RARP (28.9%) between 1992 and 2014. Logistic regression analyses were used to test the association between type of surgery and PSMs in each preoperative risk group (low vs. intermediate vs. high) after adjusting for confounders.

Results: Overall, 21.6% patients had PSMs. RARP was associated with a lower rate of PSMs in low-risk (11.5 vs. 15.4%, P = 0.01), intermediate-risk (18.9 vs. 23.5%, P = 0.008), and high-risk patients (19.7 vs. 30.1%, P<0.001). In multivariable analyses, after stratification according to risk group categories, no difference in PSMs between RARP and ORP was observed for low-risk (odds ratio [OR] = 0.87, P = 0.46) and intermediate-risk patients (OR = 0.84, P = 0.19). Conversely, RARP was associated with lower odds of PSMs in high-risk patients (OR = 0.69, P = 0.04). Similar results were observed when our analyses were repeated after accounting for pathological characteristics, in patients treated between 2006 and 2014 and in a cohort of men treated by high-volume surgeons (all P≤ 0.03).

Conclusions: The introduction of RARP at our institution led to a significant reduction in the risk of PSMs in patients with PCa with high-risk disease.