Tumour contact surface area as a predictor of postoperative complications and renal function in patients undergoing partial nephrectomy for renal tumours

Objectives: To evaluate the ability of original tumour contact surface area (CSA) to predict postoperative complications and renal function impairment in a series of patients who underwent elective partial nephrectomy (PN) for renal masses. Materials and Methods: We analysed the clinical records of 531 consecutive patients who underwent elective PN because of a suspicion of kidney cancer at five academic, high-volume centres between January 2014 and December 2016. Each participating centre evaluated prospectively the radiological images to evaluate the CSA and to assign a PADUA score. Several expert surgeons performed the surgical procedures in each participating centre. Binary logistic regression was used to perform both univariable and multivariable analyses to identify predictors of postoperative complications. Linear regression analysis was used to identify independent predictors of absolute change in estimated glomerular filtration rate (eGFR; ACE). Results: The median (interquartile range) CSA value was 14.2 (7.4–25.1) cm2. A total of 349 tumours (65.7%) had a CSA ≤ 20 cm2 and the remaining 182 (34.3%) had a CSA > 20 cm2. PNs were performed using an open approach in 237 (44.6%) cases, a pure laparoscopic approach in 152 cases (28.6%), and a robot-assisted approach in the remaining 142 cases (26.7%). Multivariable analyses found that only age (odds ratio [OR] 1.037, 95% confidence interval [CI] 1.018–1.057) and PADUA score (OR 1.289, 95%CI 1.132–1.469) were independent predictors of postoperative complications. Tumour CSA (OR 1.020, 95%CI 1.010–1.030) was found to be an independent predictor of postoperative complications only when PADUA score was removed from the model. Age (from −0.639 to −0.306; P < 0.001); body mass index (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 tumour CSA (from −0.260 to −0.048; P = 0.005) were found to be independent predictors of ACE. Conclusions: Tumour CSA is an independent predictor of postoperative renal function. Conversely, at multivariable analysis, PADUA score outperformed tumour CSA to predict postoperative complications after PN. The complexity of The Leslie et al. formula for calculating tumour CSA is a potential limitation with regard to its diffusion and application in clinical practice