Predicting Surgical Outcomes in Partial Nephrectomy: Clinical Utility and External Validation of the C-Angle...

This study was designed to perform the first external validation of the centrality angle (C-angle) as a practical nephrometry score for predicting tumor difficulty and surgical results in patients undergoing partial nephrectomy (PN).

This retrospective study included 176 patients who underwent PN between 2015 and 2025. Using coronal computed tomography measurements, patients were categorized into Group 1 (C-angle < 45°, n = 80) and Group 2 (C-angle ≥ 45°, n = 96). The two groups were compared for baseline demographics, tumor properties, and surgical results. The C-angle's correlation with existing nephrometry scores and its association with postoperative complications were also assessed.

Group 2 had significantly larger tumors (39.1 vs. 26.5 mm), alongside higher RENAL and PADUA scores (p < 0.001). The C-angle positively correlated with RENAL (r = 0.416) and PADUA (r = 0.430) scores, and negatively with the C-index (r = - 0.600) (p < 0.001 for all). In on-clamp PN, warm ischemia time and estimated blood loss were significantly higher in Group-2 (p < 0.001 and p = 0.004, respectively). Group-2 also had prolonged hospital stays (p = 0.005) and lower preserved renal function at postoperative 6-month (p = 0.048). ROC analysis predicting Clavien-Dindo ≥ 2 complications revealed the C-angle had an Area Under the Curve (AUC) of 0.688, comparable to the RENAL (0.623), PADUA (0.643), and C-index (0.682) scores, with no significant difference on pairwise DeLong testing (all p > 0.05).

The C-angle is a practical and valid nephrometry score for predicting tumor complexity and surgical outcomes in patients undergoing PN. Its significant correlation with established scoring systems supports its value as an adjunctive parameter in clinical decision-making.