Incremental Value of Iodine-125 Seed Implantation After Bronchial Artery Chemoembolization in Immunotherapy-Treated Advanced Lung Squamous Cell Carcinoma with Hemoptysis: A Retrospective Cohort Study Using Inverse Probability of Treatment Weighting

Background: The incremental value of iodine-125 (I-125) seed implantation in advanced refractory lung squamous cell carcinoma (LUSC) with hemoptysis treated with bronchial artery chemoembolization (BACE) and immunotherapy remains unclear. Methods: This retrospective cohort study included 90 patients treated between June 2023 and June 2025. Patients receiving BACE plus immunotherapy were classified according to whether I-125 seed implantation was performed within 7 days after BACE: G1, BACE plus immunotherapy (n = 42), and G2, BACE, I-125 seed implantation, and immunotherapy (n = 48). Inverse probability of treatment weighting (IPTW) served as the primary adjustment method. Results: After IPTW, baseline covariates were well balanced; propensity score matching yielded 26 patients per group. Compared with G1, G2 was associated with longer hemoptysis-free survival (not reached vs. 11 months; HR = 0.34, 95% CI 0.18–0.64, p < 0.05), overall survival (19 vs. 14 months; HR = 0.26, 95% CI 0.15–0.44, p < 0.05), and progression-free survival (12 vs. 9 months; HR = 0.34, 95% CI 0.21–0.56, p < 0.05). The 6-month objective response rate (ORR) and disease control rate (DCR) were higher in G2, whereas no significant difference in 24-h hemostasis or recorded grade 3 or higher adverse events was observed. Conclusions: Adding I-125 seed implantation to BACE plus immunotherapy was associated with improved outcomes in selected patients, and prospective validation is warranted.