A proposed staging system for intrahepatic cholangiocarcinoma involving the hilar

Background: Intrahepatic cholangiocarcinoma involving the hepatic hilum (h-ICC) is a rare and aggressive malignancy with heterogeneous clinical outcomes. Current staging systems are often inadequate for prognostic prediction in this subgroup. This study aimed to identify key prognostic factors and develop a novel, clinically applicable survival classification model for patients with h-ICC undergoing surgery. Methods: We retrospectively analyzed 333 patients with h-ICC at West China Hospital from 2003 to 2023. Baseline clinical, laboratory, and imaging data were collected. Univariate and multivariate Cox regression analyses identified independent prognostic factors. A classification and regression tree (CART) model was constructed to stratify patients based on overall survival. Model performance was assessed using ROC curves and Brier scores. Results: Intrahepatic metastasis (HR = 1.569, P = 0.0489) and regional lymph node metastasis (HR = 2.227, P < 0.001) were identified as independent prognostic factors. A CART-based survival model stratified patients into four risk groups based on regional lymphatic metastasis, local organ metastasis, intrahepatic metastasis, total bilirubin level (cutoff: 192.6 mu mol/L), and tumor size (cutoff: 4.65 cm). Based on these variables, we constructed a nomogram to improve clinical availability. After verification, the proposed model demonstrated good discriminatory ability and calibration. Conclusion: Intrahepatic and lymphatic metastases are critical prognostic indicators in h-ICC. The newly developed CART-based staging system offers improved survival stratification and may guide personalized treatment planning in this patient population.