Margin, Ischemia and Complications (MIC) after laparoscopic and robot-assisted partial nephrectomy for completely endophytic renal masses: a multi institutional analysis
International guidelines states that renal tumors <7 cm are best managed by nephron sparing surgery (NSS). A very challenging scenario is represented by renal masses that are completely intraparenchymal. Surgical removal of these tumors presents greater technical difficulties and higher risk of peri and post-operative complications. In 2012 Buffi et al proposed a new system to evaluate success after partial nephrectomy (PN), the Margin, Ischemia and Complications (MIC).According to this newly proposed scoring system, an optimal PN is accomplished when surgical margins (SM) are negative, WIT was ≤20 minutes and no major complication (Clavien-Dindo grade 3-4) were observed. The use of this simple system could be of paramount importance to compare and evaluate different approach used to perform PN. Aim of this study is to evaluate differences between laparoscopic (LPN) and robot-assisted PN (RAPN) using the MIC system in completely endophytic renal masses.
Materials and Methods
This is a retrospective multicenters study. Datas of LPN and RAPN were extracted from the medical database of each institute. Patients that performed LPN and/or RAPN from 2008 and 2014 were selected for this study. Before surgery, all patients underwent a computed tomography (CT) scan or magnetic resonance imaging (RMI) in order to evaluate the clinical stage and the anatomical characteristics of the tumors. Based on image of CT scan or RMI, a Preoperative Aspect and Dimension Used for an Anatomical (PADUA) score was assigned to each patients. Patients who received 3 points in the exophytic rate of PADUA classification, which is used to describe the exophytic\endophytic properties of the renal mass, entered in this study. During surgery, a laparoscopic US guidance was used in all cases to identified the renal mass and to help the surgeon to observe the tumor's margin. According to MIC scoring system, an optimal PN is accomplished when surgical margins (SM) are negative, warm ischemia time (WIT) was ≤20 minutes and no major complication (Clavien-Dindo grade 3-4) were observed. Non parametric Mann-Whitney test was used for continuous variables, Pearson x2 correlation for categorical variables.
66 patients were enrolled in this study (31 for LPN and 35 for RAPN group). No differences were observed beetween the two groups in age, gender, BMI, ASA and Charlson comorbidity index (CCI). All renal masses in the LPN and RAPN presented small clinical size (median 2.1 and 2.4 cm respectively; p-value:0.129). LPN group presented an higher median PADUA score than RAPN group (10 vs 9; p-value 0.018). No differences were observed in PADUA class risk distribution beetween groups (intermediate: 38.7 vs 57.1% high: 61.3 vs 49.9% p-value: 0.135). The PADUA low risk group was not presented in the two cohort. The median WIT was 23.1 (IQR: 17-29) in LPN group and 21.2 (IQR: 18-26) for RAPN group (p-value: 0.257). No differences were observed in surgery duration (p-value:0.356), intra-operative complications rate (p-value: 0.062) and estimated blood loss (p-value: 0.115) beetwen groups. No major complications (dindo grade 3-4) and PSM occurred in the two groups. The MIC rate was 51.6% in LPN and 71.4% in RAPN group, but it was statistically significant (p-value: 0.101). Interestingly, the only difference observed in this report beetween LPN and RAPN was the post-operative eGFR. RAPN group presented a higher median post-operative eGFR than LPN group (p-value: <0.001).
The findings of this study shows that MIC score system is a simple and useful tool to report and compare different surgical approach.This system is similar to the trifecta outcomes proposed and validated by other groups of authors. Hung et al, definited the trifecta outcomes when there was negative SM, minimal renal function decrease and no urological complications. Khalifeh et al, definited trifecta outcomes as a WIT ≤25 minutes, negative SM and no intra and post-operative complications. The MIC system is based on aspects validated by literature. Recently a panel of experts proposed that WIT should not ideally exceed 20 minutes and every minutes counts when the hilum is clamped. The Clavien-Dindo classification is the most validated tool to standardized and report surgical complications. Mottrie defined the MIC score system simple to use and encouraged new research to assess is efficacy, especially by comparing its use in different surgical approaches (OPN, LPN and RAPN). This study showed the feasibility and safety of LPN and RAPN for endophytic renal masses, with similar results in terms of negative surgical margin, WIT <20 minutes and no major complications. LPN and RAPN presented similar outcomes if performed by expertised surgeons. A recent study showed that there was no difference between RAPN and LPN in complex tumors (median renal score 8), and this was explained by the authors on the basis of experienced surgeon’s experience in laparoscopic and robotic surgery in high volume centers. The transition from LPN to RAPN is simple and can be associated with immediate improvements in perioperative parameters for surgeons with a solid baseline experience with LPN. RAPN may reduce the technical difficulties of LPN , especially in complex cases, but a laparoscopic skills are important in robotic surgery. LPN and RAPN are safety and no invasive procedures with similar results if performed by expertised surgeons. In our study RAPN group presented an highest eGFR than LPN group. This aspect also supported the safety and the efficacy of RAPN. In this study we evaluted only the safety of mini-invasive surgery for endophytic renal masses using the MIC system. We did not evaluated the efficacy of LPN and RAPN in terms of oncological results.
This study showed the feasibility and safety of LPN and RAPN for endophytic renal masses, with similar results in terms of negative surgical margin, WIT <20 minutes and no major complications. LPN and RAPN presented similar outcomes if performed by expertised surgeons.RAPN may reduce the technical difficulties of LPN but LPN represents a feasible, safe and effective treatment for selected patients diagnosed with endophytic masses.Our report showed that the MIC score system is simple and useful to report and compare different surgical approach. The use of nephrometry score system may help the surgeon in predicting MIC and in planning the best surgical strategy for patients.
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