Sequential immune checkpoint inhibition after palliative radiotherapy in patients with advanced head and neck squamous cell carcinoma: A retrospective cohort study

Head and neck squamous cell carcinoma (HNSCC) frequently presents at an advanced stage, where curative options are often not feasible. Palliative radiotherapy (RT) can relieve symptoms and improve performance status, potentially enabling systemic therapy. Immune checkpoint inhibitors (ICIs) have a survival benefit in recurrent and metastatic HNSCC; however, the optimal sequencing of RT and ICIs remains to be elucidated. The present study aimed to evaluate the clinical outcomes of ICI therapy administered after palliative RT in patients with advanced HNSCC. Consecutive patients with advanced HNSCC treated at The University of Tokyo Hospital (Tokyo, Japan) between January 2017 and December 2024 were retrospectively reviewed. Eligible patients received initial palliative RT, with or without subsequent ICIs within 6 months (RT-ICI vs. RT groups). Clinical data, including demographics, RT parameters, treatment regimens and outcomes, were collected. Overall survival (OS) and progression-free survival (PFS) analyses were performed using the Kaplan-Meier method and Cox proportional hazards models. Among 74 patients (median age, 75 years; 82% male), 17 received ICIs following RT. The RT-ICI group achieved a 2-year OS rate of 55.8% compared with 5.7% in the RT group (P