Supplementary Material for: Ferritin to Transferrin Ratio: a new prognostic factor for renal cell carcinoma

Objectives: To assess the prognostic value of the preoperative serum ferritin-to-transferrin ratio (FTR) in renal cell carcinoma (RCC). Methods：We retrospectively reviewed data from 226 patients who underwent surgery for non-metastatic RCC at our institution between January 1, 2012, and June 30, 2021. Time-dependent receiver operating characteristic (timeROC) analysis identified the optimal FTR cut-off, dividing patients into high and low FTR groups. Propensity score matching (PSM) adjusted for baseline differences. Recurrence-free survival (RFS) and overall survival (OS) were analyzed using the Kaplan–Meier method and Cox regression, with a nomogram validating the results. Results: The timeROC analysis showed a 5-year area under the curve (AUC) of 0.786 for FTR, with 68.4% sensitivity and 86.7% specificity at a cut-off of 177.1. High FTR and clinical stage were independent risk factors for OS and RFS. The hazard ratios (HR) for OS and RFS in the high and low FTR groups were 2.598(1.087-6.213), P=0.032 and 2.591(1.105-6.074), P=0.029, respectively. Kaplan–Meier curves showed significant differences post-PSM (log rank P<0.05). The nomogram validation indicated high predictive accuracy with a C-index of 0.867 (95% CI: 0.836-0.899) for OS and 0.808 (95% CI: 0.764-0.852) for RFS. Conclusion：Our findings suggest that FTR may serve as an independent prognostic risk factor in patients with locally and locally advanced renal cell carcinoma.