Margins, ischaemia and complications rate after laparoscopic partial nephrectomy: impact of learning curve and tumour anatomical characteristics

Objectives: To present our laparoscopic partial nephrectomy (LPN) results according to the margin, ischaemia and complications (MIC) system recently proposed for the standardized reporting of partial nephrectomy (PN) outcomes. To assess the role of learning curve and tumour anatomical characteristics on the outcomes by using MIC system.

Patients and methods: Data were obtained from our prospectively maintained LPN database, including only patients who underwent LPN performed with vascular clamping. According to the MIC system definition, the goal of LPN was reached (i.e. MIC was achieved) when surgical margins were negative, warm ischaemia time (WIT) was <20 min and no major complications occurred. Patients were stratified by quartiles of distribution, named LPN eras 1-4, and MIC rates in different LPN eras were compared, evaluating the impact of learning curve and tumour anatomical characteristics (as assessed by Preoperative Aspects and Dimensions Used for an Anatomical [PADUA] score on the outcomes.

Results: The study population consisted of 206 patients. The overall MIC rate was 63.1%: it progressively increased along the learning curve, reaching 84.9% in LPN era 4 (P < 0.001). PADUA-score risk group categories were inversely correlated with MIC score (P = 0.001). When simultaneously considering the effects of both LPN eras and PADUA-score risk group categories, a trend towards a higher MIC rate was found in the latest series, regardless of tumour anatomical characteristics. When MIC score components were separately analysed, WIT decreased significantly from LPN era 1 to LPN era 4 (P < 0.001) and from PADUA-score risk group categories 3 to 1 (P = 0.001) A trend towards a decrease in the complication rate along the learning curve was observed (P = 0.251), while LPN era and PADUA score together significantly influenced the complications rate (P < 0.001). The positive surgical margin rate was very low (2.9% overall) and stable throughout the case study.

Conclusion: The MIC rate increased with surgeon's experience and decreased when complex lesions were treated. The MIC system was found to be an easy, useful and reproducible tool to report LPN data series.