Retroperitoneal Robot-assisted Partial Nephrectomy: A Systematic Review and Pooled Analysis of Comparative Outcomes.

Context: Robot-assisted partial nephrectomy (RAPN) has gained increasing popularity as primary minimally invasive surgical treatment for localized renal tumors, and it has preferably been performed with a transperitoneal approach. However, the retroperitoneal approach represents an alternative approach given potential advantages. Objective: To provide an updated analysis of the comparative outcomes of retroperitoneal RAPN (R-RAPN) versus transperitoneal RAPN (T-RAPN). Evidence acquisition: A systematic review of the literature was performed up to September 2021 using MEDLINE, EMBASE, and Web of Science databases, according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) recommendations. A sensitivity analysis was performed considering only matched-pair studies. Evidence synthesis: Seventeen studies, which were published between 2013 and 2021, were retrieved. None of them was a randomized clinical trial. Among the 6,266 patients included in the meta-analysis, 2261 (36.1%) and 4,005 (63.9%) underwent R-RAPN and T-RAPN, respectively. No significant difference was found in terms of baseline features. The T-RAPN group presented a higher rate of male patients (odds ratio [OR]: 0.86, p = 0.03) and larger tumor size (weighted mean difference [WMD]: 0.2 cm; p = 0.003). The R-RAPN group reported more frequent posterior renal masses (OR: 0.23; p < 0.0001). The retroperitoneal approach presented lower estimated blood loss (WMD: 30.41 ml; p = 0.001), shorter operative time (OT; WMD: 20.36 min; p = 0.0001), and shorter length of stay (LOS; WMD: 0.35 d; p = 0.002). Overall complication rates were 13.7% and 16.05% in the R-RAPN and T-RAPN groups, respectively (OR: 1.32; p = 0.008). There were no statistically significant differences between the two groups regarding major (Clavien-Dindo classification ≥3 grade) complication rate, "pentafecta" achievement, as well as positive margin rates. When considering only matched-pair studies, no difference between groups was found in terms of baseline characteristics. Posterior renal masses were more frequent in the R-RAPN group (OR: 0.6; p = 0.03). Similar to the analysis of the entire cohort, R-RAPN reported lower EBL (WMD: 35.56 ml; p < 0.0001) and a shorter OT (WMD: 18.31 min; p = 0.03). Overall and major complication rates were similar between the two groups. The LOS was significantly lower for R-RAPN (WMD: 0.46 d; p = 0.02). No statistically significant difference was found between groups in terms of overall PSM rates. Conclusions: R-RAPN offers similar surgical outcomes to T-RAPN, and it carries potential advantages in terms of shorter OT and LOS. Available evidence remains limited by the lack of randomized clinical trials. Patient summary: In this review of the literature, we looked at comparative outcomes of two surgical approaches to robot-assisted partial nephrectomy. We found that the retroperitoneal technique offers similar surgical outcomes to the transperitoneal one, with potential advantages in terms of shorter operative time and length of hospital stay.