Determinants of survival benefit from endobiliary radiofrequency ablation for extrahepatic cholangiocarcinoma according to tumor stage, systemic therapy, and session number

Background: Endobiliary radiofrequency ablation (EB-RFA) has emerged as a promising adjunct capable of prolonging survival in patients with extrahepatic cholangiocarcinoma (eCCA), though its clinical utility remains unclear. Key unresolved issues include the impact of metastatic status, systemic therapy, and the number of ablation sessions on EB-RFA effectiveness. In this study, we aimed to address these factors to define the role and indications for EB-RFA better. Methods: This multicenter, retrospective study included 336 patients with unresectable eCCA who underwent endoscopic biliary stenting with (n=121) or without (n=215) EB-RFA. The primary outcome was overall survival (OS), which was analyzed separately for patients with and without distant metastases. Results: Among patients without distant metastases, EB-RFA significantly improved OS compared to stenting alone (median 527 vs. 300 days, P<0.001), regardless of systemic therapy (with systemic therapy: 611 vs. 344 days, P=0.005; without systemic therapy: 415 vs. 282 days, P=0.040). Patients who received multiple EB-RFA sessions (≥2) had the longest OS (573 days), followed by those who received single sessions (426 days) and those without ablation (300 days) (P=0.002). No OS benefit was observed in patients with distant metastases. However, among those receiving systemic therapy, multiple EB-RFA sessions significantly improved OS compared to non-ablation (274 vs. 163 days, P=0.044). Adverse event rates were comparable between patients with and without EB-RFA. Conclusions: EB-RFA significantly improved the survival of patients with locoregional eCCA. In cases of metastasis, multiple sessions may offer additional benefits when combined with systemic therapy.