Comparison of Efficacy and Safety of Combined Chemoimmunotherapy With or Without Radiation Therapy for Stage IVB Esophageal Squamous Cell Carcinoma: A Multicenter Propensity Score Matching Analysis.

ABSTRACT

PURPOSE: This study aimed to compare the efficacy and safety of combining first-line chemoimmunotherapy with radiation therapy versus chemoimmunotherapy alone in patients with stage IVB esophageal squamous cell carcinoma (ESCC). METHODS AND MATERIALS We retrospectively examined 409 patients with stage IVB ESCC who received first-line chemotherapy and anti-PD-1 antibody, with or without radiation therapy of ≥40 Gy radiation dose to primary lesion, from 4 academic cancer centers between October 2018 and December 2022. Propensity score matching was conducted to minimize the potential confounding effects. RESULTS: In the overall cohort of 409 patients, the group that received additional radiation therapy had superior overall survival (OS) (hazard ratio [HR], 0.51; 95% CI, 0.39-0.66; P < .001) and progression-free survival (PFS) (HR, 0.52; 95% CI, 0.40-0.66; P < .001) compared to the group that received chemoimmunotherapy alone. After 11 propensity score matching, matching age, tumor location, and metastatic sites, a total of 250 patients were selected for further analysis. The results remained consistent and showed that the addition of radiation therapy significantly improved OS and PFS (median OS, 24.9 vs 14.6 months; P = .003; median PFS, 14.2 vs 10.6 months; P = .002). Multivariate Cox analysis including tumor location, T stage, metastatic sites, and treatment modality, revealed that radiation therapy was an independent prognostic factor for both OS (HR, 0.57; 95% CI, 0.41-0.81) and PFS (HR, 0.63, 95% CI, 0.47-0.86). Subgroup analyses revealed significant OS prolongation in patients with nonregional lymph node metastases only who received radiation therapy (HR, 0.49; 95% CI, 0.34-0.70). No OS survival benefit was observed in those with distant organ metastases (HR, 0.72; 95% CI, 0.46-1.13). Regarding safety, the group receiving additional radiation therapy had higher incidences of grade 3 to 4 lymphopenia (74.4% vs 17.7%, P < .001) and esophagitis (11.2% vs 2.4%, P = .006). CONCLUSIONS: The addition of radiation therapy to chemoimmunotherapy improved the survival of stage IVB ESCC patients with nonregional lymph node metastasis.