Innovative 3D method predicts surgery outcomes by calculating real contact surface of renal tumor.

Objective: The Contact Surface Area (CSA) is a predictor for peri-operative parameters and represents the contact area between the tumor and the organ. A precise method for calculating CSA is yet to be found. We tested a new CSA calculation method as a predictor of intra-operative parameters in robot assisted partial nephrectomy (RAPN).

Materials & methods: The study population consisted of all consecutive patients treated with RAPN at a single high-volume European institution (between 2020 to 2023; 82 patients). We proposed a new method to measure the real value of CSA using an algorithm that leverages the geometry of kidneys and tumors obtained from 3D reconstruction. These reconstructions were obtained using the certified software Materialized Mimics InPrint. The peri-operative parameters of patients were recorded in an anonymous database. We explored the correlation between real CSA (RCSA), CSA of Hsieh (HCSA), PADUA and R.E.N.A.L. scores with peri-operative parameters using Spearman's correlation. Furthermore, we examined which of RCSA, PADUA and R.E.N.A.L. score better describes the intra-operative parameters, Warm Ischemia Time (WIT), Operating Time (OT), and Estimated Blood Loss (EBL) using Receiver Operating Characteristic (ROC) curve analysis. Multivariable linear regression analyses were performed.

Results: Seventy-eight patients were prospectively enrolled. We observed a significant correlation between RCSA and WIT (P < 0.001), OT (P < 0.001) and EBL (P < 0.001). Moreover, RCSA outperformed both the PADUA and R.E.N.A.L. score as demonstrated in the ROC curve analysis. In ROC analysis was chosen a threshold for each of the parameters: for WIT 20 minutes, for OT 180 minutes and for EBL 200 mL. At multivariable regression analysis, RCSA emerged as the only independent predictor for WIT (P = 0.002), OT (P = 0.01) and EBL (P < 0.001).

Conclusions: Our original 3D RCSA calculation method was associated to intra-operative surgical outcomes. As compared to PADUA and RENAL score, our calculated RCSA represented a more reliable predictor of intra-operative parameters.