Evolving role of radiation therapy in advanced/metastatic intrahepatic cholangiocarcinoma

This review evaluates the role of stereotactic body radiation therapy (SBRT) in advanced/metastatic intrahepatic cholangiocarcinoma (iCCA), highlighting its efficacy, integration with systemic therapy, and potential for resection or transplantation. SBRT is emerging as a transformative, non-invasive treatment for iCCA, extending beyond palliation. SBRT with a biologically effective dose > 75 Gy improves survival in unresectable iCCA, with median overall survival (mOS) of 15-24 months, significantly surpassing lower-dose regimens. Advanced motion management techniques like fiducial tracking and gating achieve > 70% local control at 1 year. In metastatic iCCA, hypo-fractionated SBRT provides symptom relief with mOS of 6-9 months and reduced toxicity. Neoadjuvant SBRT increases R0 resection rates to 60%-75% in borderline resectable cases, compared to 30%-40% with chemotherapy alone. SBRT combined with systemic therapy expands eligibility for liver transplantation, achieving 3-year post-transplant survival > 65%. SBRT is a transformative therapy for iCCA, improving control, survival, and eligibility for curative treatments. Further research is needed to optimize protocols and patient selection.