The Rboost causal model can identify patients who are most likely to benefit among HCC-BDTT patients. Adherence to the individualized recommendation improves survival. This data-driven tool offers vital support for precision surgical decision-making in this high-risk disease.

This dual-center study recruited 151 HCC-BDTT patients who underwent radical hepatectomy (training cohort: 92; validation cohort: 59). An XGBoost-based R-learner (Rboost) algorithm was developed to estimate the individualized treatment effect (ITE) on 5-year overall survival (OS) between BDR and NBDR. Patients were stratified into ITE tertiles: BDR-recommended, ambiguous benefit, and NBDR-recommended. Model performance assessed with heterogeneity metrics (C-for-benefit, adjusted Qini index). Survival outcomes were compared within ITE strata between surgeries concordant and discordant with model recommendations (Kaplan-Meier/log-rank). Two-year disease-free survival (DFS) served as a treatment-proximal validity check.

Inclusion Criteria:

• Pathologically confirmed HCC with BDTT;
• Absence of extrahepatic malignancies at the time of HCC diagnosis;
• Undergone R0 curative hepatectomy;
• No prior antitumor therapies, such as chemotherapy or immunotherapy, before surgery;
• Availability of preoperative imaging (CT or MRI) with standardized tumor evaluation.

Exclusion Criteria:

• Pathological findings indicating concurrent cholangiocarcinoma and HCC;
• Loss to follow-up, preventing outcome evaluation, or insufficient clinical data for analysis.
• Significant comorbidities (e.g., severe cardiac or renal failure) that could affect surgical outcomes.

This dual-center observational study was approved by the Institutional Review Board (IRB) of the First Affiliated Hospital of Sun Yat-sen University (approval number: [2023]016), with a waiver of informed consent. This study retrospectively enrolled patients with HCC from two campuses: Yuexiu campus (Center 1; January 2011-August 2020) and Huangpu campus (Center 2; August 2014-August 2020).

All primary data are available from the corresponding author upon reasonable request.