Tumor contact surface area as predictor of postoperative complications and renal function in patients undergoing partial nephrectomy for renal tumors

Aim of the study: To evaluate the ability of original tumor contact surface area (CSA) proposed by Leslie et al to predict postoperative complications and renal function impairment in a series of patients who underwent elective PN for renal masses. Materials and methods: We analyzed the clinical records of 531 consecutive patients who underwent elective PN because of a suspicion of kidney cancer at five academic, high-volume centers from January 2014 to December 2016. Each participant Center evaluated prospectively the radiologic images to assign the CSA and the PADUA score. Several expert surgeons performed the surgical procedures in each participant Center. Binary logistic regression was used to perform both univariable and multivariable analyses looking for predictors of postoperative complications. Linear regression analysis was used to identify independent predictors of absolute change in eGFR (ACE). Results: The median value of CSA was 14.2 (IQR 7.4–25.1) cm2. 349 (65.7%) tumors showed a CSA ≤ 20 cm2 and the remaining 182 (34.3%) a CSA > 20 cm2. PNs were performed using an open approach in 237 (44.6%) cases, a pure laparoscopic approach in 152 (28.6%), and a robot-assisted approach in the remaining 142 (26.7%). Multivariable analyses showed that only age (OR 1.037 – 95%CI 1.018–1.057) and PADUA score (OR 1.289 – 95%CI 1.132–1.469) turned out to be independent predictors of postoperative complications. Tumor CSA (OR 1.020 – 95%CI 1.010–1.030) resulted independent predictor of postoperative complications only when PADUA score was removed from the model. Age (from −0.639 to −0.306; p < 0.001); BMI (from 0.267 to 1.076; p = 0.001), age-adjusted Charlson score (from −3.193 to −0.259; p = 0.02), preoperative eGFR value (from −0.939 to −0.862; p < 0.001) and tumor CSA (from −0.260 to −0.048; p = 0.005) turned out to be independent predictors of ACE. Discussion: Tumor CSA is an independent predictor of postoperative renal function. Conversely, at multivariable analysis PADUA score outperformed tumor CSA to predict postoperative complications after PN. The complexity of Leslie’s formula to calculate the tumor CSA value is a potential limitation of its diffusion and application in the clinical practice