PURPOSE: The purpose of this study is to determine the utility of the CANLPH score as a predictive biomarker for patients with advanced and metastatic renal cell carcinoma (a/mRCC). By validating its prognostic value, this study aims to contribute to more personalized treatment strategies for a/mRCC. METHODS: In a multicenter retrospective study by the JK-FOOT consortium, we analyzed data from 309 a/mRCC patients undergoing ICI-based therapy. The CANLPH score-a composite marker of C-reactive protein to albumin ratio (CAR), neutrophil to lymphocyte ratio (NLR), and platelet to hemoglobin ratio (PHR)-for its prognostic accuracy in predicting cancer-specific survival (CSS). Advanced statistical methods, including receiver operating characteristic (ROC) curve analysis, Cox proportional-hazard regression, and Harrell's concordance index (C-index), were employed to assess its predictive capacity against established factors. RESULTS: The median follow-up period was 17 months, revealing two-year and five-year overall survival rates of 76.8% and 62.4%, respectively, with CSS rates at 78.3% and 66.2%. The CANLPH score well stratified survival outcomes of ICI-based treatment for RCC patients (HR 5.71
P <
0.0001). C-index analysis demonstrated that the CANLPH score had the highest predictive potency for CSS among models, including IMDC score. Multivariate analysis confirmed the CANLPH score (HR, 5.59
P = 0.0007) and Karnofsky performance status (HR, 2.59
P = 0.0032) as independent prognostic factors for CSS. CONCLUSIONS: The CANLPH score emerges as a critical tool in the a/mRCC therapeutic landscape, enabling precise prediction of patient outcomes with ICI-based therapies. Limitations include the retrospective design and the single national cohort. Prospective validation studies are warranted.