Immunochemotherapy alone or immunochemotherapy plus subsequent locoregional radiotherapy in de novo metastatic nasopharyngeal carcinoma

Background: To demonstrate whether the benefit of locoregional radiotherapy in de novo metastatic nasopharyngeal carcinoma remains in the immunotherapy era and which patients can benefit from radiotherapy.Materials and methods: A total of 273 histopathology-confirmed de novo metastatic nasopharyngeal carcinoma was enrolled between May 2017 and October 2021 if receiving immunochemotherapy with or without subsequent intensity-modulated radiotherapy to the nasopharynx and neck. We compared the progression-free survival, overall survival, and safety between the two groups. Additionally, subgroup analysis was conducted and a scoring model was developed to identify suitable patients for radiation.Results: There were 95 (34.8 %) patients with immunochemotherapy alone, and 178 (65.2 %) with immunochemotherapy plus subsequent locoregional radiotherapy. With a median follow-up time of 18 months, patients with immunochemotherapy plus subsequent radiotherapy had higher 1-year progression-free survival (80.6 % vs. 65.1 %, P < 0.001) and overall survival (98.3 % vs. 89.5 %, P = 0.001) than those with immunochemotherapy alone. The benefit was retained in multivariate analysis and propensity score-matched analysis. Mainly, it was more significant in patients with oligometastases, EBV DNA below 20,200 copies/mL, and complete or partial relapse after immunochemotherapy. The combined treatment added grade 3 or 4 anemia and radiotherapy-related toxicities. Conclusion: Immunochemotherapy plus subsequent locoregional radiotherapy prolonged the survival of de novo metastatic nasopharyngeal carcinoma with tolerable toxicities. A scoring model based on oligometastases, EBV DNA level, and response after immunochemotherapy could facilitate individualized management.