ObjectiveImmunotherapy combined with chemotherapy is currently the first-line treatment for metastatic head and neck squamous cell carcinoma (HNSCC). This study aims to evaluate whether adding metastasis-directed radiotherapy (MDRT) to immunotherapy and chemotherapy could improve the survival rate of patients with metastatic HNSCC.Materials and methodsA retrospective analysis was conducted on patients with HNSCC who developed distant metastases after curative treatment. Systemic treatment was determined by the multidisciplinary team, with a programmed cell death-1 (PD-1) inhibitor combined with chemotherapy as the primary approach. The feasibility of radiotherapy was evaluated by clinical and imaging examinations. Stereotactic body radiotherapy (SBRT) was used to deliver different doses according to the number and location of metastatic lesions. Kaplan-Meier method was used to estimate survival, and Cox regression analysis was performed to evaluate the association between clinical factors and survival outcomes.ResultsFrom January 2018 to June 2023, a total of 94 patients with 164 metastatic sites were included for the analysis. The most common primary tumor was the nasopharynx (77.7%), with the lung being the most frequent site of metastasis (46.8%), followed by bone (37.2%). Radiotherapy was administered to 276 metastatic lesions, with a median dose of 52.3 Gy (range: 24-60 Gy). The median overall survival (OS) was 43.0 months (range: 20.2-65.8). The OS rates at 2 and 5 years were 70.1% (95% CI, 59.7-80.5%) and 30.1% (95%CI 11.7-48.5%), respectively. Univariate and multivariate analysis showed that the number of metastases and the location of the primary tumor were significantly associated with OS.ConclusionsIn patients with metastatic HNSCC, MDRT combined with immunotherapy and chemotherapy can effectively improve local control and OS. These findings warrant further validation through prospective clinical trials: