Comparison of robot-assisted and open retropubic radical prostatectomy for risk of biochemical progression in men with positive surgical margins

Abstract

Objective: Robot-assisted radical prostatectomy (RARP) is a minimally invasive alternative to open retropubic radical prostatectomy (RP), and is reported to offer equivalent oncologic outcomes while reducing perioperative morbidity. However, the technique of extirpation can differ based on the usage of thermal energy and coagulation during RARP, which may alter the risk of finding a positive surgical margin (PSM) as cautery may destroy residual cancer cells. We sought to evaluate whether the method of surgery (RP vs RARP) affects the rate of biochemical recurrence (BCR) in patients with PSMs.

Materials & methods: The Columbia University Urologic Oncology Database was reviewed to identify patients who underwent RP and RARP from 2000 to 2010 and had a PSM on final pathology. BCR was defined as a postoperative prostate-specific antigen (PSA) ≥0.2 ng/mL. The Kaplan-Meier analysis was utilized to calculate BCR rates based on the method of surgery. Cox regression analysis was performed to determine if the method of surgery was associated with BCR.

Results: We identified 3267 patients who underwent prostatectomy, of which 910 (28%) had a PSM. Of those with a PSM, 337 patients had available follow-up data, including 229 who underwent RP (68%) and 108 who underwent RARP (32%). At a mean follow-up time of 37 months for the RP group, 103 (46%) patients demonstrated BCR; at a mean follow-up time of 44 months for the RARP group, 62 (57%) patients had a BCR (p=0.140). Two-year BCR-free rates for RP vs RARP were 65% and 49%, respectively (log-rank p<0.001). However, after controlling for age, PSA, grade, and year of surgery, the surgical method was not significantly associated with increased risk of BCR (HR 1.25; p=0.29).

Conclusion: Our results confirm the noninferiority of RARP to RP with regard to patients with PSMs. As such, all patients with a PSM at RP are at high risk for BCR and should be followed in the same manner regardless of the surgical approach.