The efficacy and safety of PD-1 inhibitors combined with 125I seed implantation in treating extrahepatic metastasis of hepatocellular carcinoma

Introduction Patients with advanced hepatocellular carcinoma (HCC) and extrahepatic metastases face a poor prognosis with limited treatment options. Methods We conducted a retrospective study of 84 such patients treated between January 2018 and April 2025 with either PD-1 inhibitor immunotherapy alone or in combination with iodine-125 ( 125 I) seed brachytherapy. Propensity score matching (PSM) yielded 25 patient pairs for outcome comparison. Results The combination therapy achieved significantly better local tumor control than monotherapy. Progression-free survival was prolonged with the combined treatment (median PFS 22.06 vs. 9 months, p = 0.03), although overall survival was not significantly different between the groups. Both treatments markedly reduced serum alpha-fetoprotein levels and alleviated cancer-elated pain, with significant pain score improvements from baseline in each group. No severe treatment-related complications or deaths occurred. Multivariate analysis indicated that adding 125 I seed implantation was an independent protective factor for disease progression control. Discussion In conclusion, combining PD-1 inhibitors with 125 I seed implantation is a safe and effective strategy to improve local tumor control and progression-free survival in metastatic HCC, although the benefit in overall survival is limited. Further studies are needed to optimize this combined therapy, assess systemic immune effects, and improve long-term outcomes. Clinical trial registration https://www.clinicaltrials.gov/ , identifier NCT06991907.