The IRON Study: Investigation of Robot-assisted Versus Open Nephron-sparing Surgery

Background: Current literature does not provide large-scale data regarding clinical outcomes of robot-assisted (RAPN) versus open (OPN) partial nephrectomy. Moreover, data assessing predictors of long-term oncologic outcomes after RAPN are scarce.Objective: To compare perioperative, functional, and oncologic outcomes of RAPN versus OPN, and to investigate the predictors of oncologic outcomes after RAPN. Design, setting, and participants: This study included 3467 patients treated with OPN (n = 1063) or RAPN (n = 2404) for a single cT1-2N0M0 renal mass from 2004 to 2018 at nine high-volume European, North American, and Asian institutions.Outcome measurements and statistical analysis: The study outcomes were short-term postoperative, functional, and oncologic outcomes. Regression models investigated the effect of surgical approach (open vs Robot assisted) on study outcomes, and inter-action tests were used for subgroup analyses. Propensity score matching for demo-graphic and tumor characteristics was used in sensitivity analyses. Multivariable Cox-regression analyses identified predictors of oncologic outcomes after RAPN. Results and limitations: Baseline characteristics were similar between patients receiving RAPN and OPN, with only few differences. After adjusting for confound-ing, RAPN was associated with lower odds of intraoperative (odds ratio [OR]: 0.39, 95% confidence interval [CI]: 0.22, 0.68) and Clavien-Dindo >2 postoperative (OR: 0.29, 95% CI: 0.16, 0.50) complications (both p < 0.05). This association was not affected by comorbidities, tumor dimension, PADUA score, or preoperative renal function (all p > 0.05 on interaction tests). On multivariable analyses, we found no differences between the two techniques with respect to functional and onco-logic outcomes (all p > 0.05). Overall, there were 63 and 92 local recurrences and systemic progressions, respectively, with a median follow-up after surgery of 32 mo (interquartile range: 18, 60). Among patients receiving RAPN, we assessed pre-dictors of local recurrence and systemic progression with discrimination accuracy (ie, C-index) that ranged from 0.73 to 0.81.Conclusions: While cancer control and long-term renal function did not differ between RAPN and OPN, we found that the intra-and postoperative morbidity- especially in terms of complications-was lower after RAPN than after OPN. Our pre-dictive models allow surgeons to estimate the risk of adverse oncologic outcomes after RAPN, with relevant implications for preoperative counseling and follow-up after surgery.Patient summary: In this comparative study on robotic versus open partial nephrec-tomy, functional and oncologic outcomes were similar between the two techniques, with lower morbidity-especially in terms of complications-for robot-assisted sur-gery. The assessment of prognosticators for patients receiving robot-assisted partial nephrectomy may help in preoperative counseling and provides relevant data to tai-lor postoperative follow-up.(c) 2023