Efficacy of metastatic lesion radiotherapy in de novo metastatic nasopharyngeal carcinoma patients receiving local regional radiotherapy and chemo-immunotherapy: a multicenter retrospective study.

Abstract

De novo metastatic nasopharyngeal carcinoma (dmNPC) exhibits heterogeneous survival outcomes. While combining chemo-immunotherapy with locoregional radiotherapy (LRRT) improves outcomes, the role of metastatic lesion radiotherapy (MLRT) remains controversial, especially in the context of immunotherapy. This study aims to evaluate MLRT's efficacy in dmNPC patients receiving chemo-immunotherapy and LRRT and establish a prognostic model for identifying MLRT beneficiaries. The study comprised of 347 dmNPC patients from four different centers. All patients received ≥2 cycles of first-line chemo-immunotherapy and LRRT. MLRT was administered to 77 patients. Prognostic factors were analyzed using Cox regression. A recursive partitioning analysis (RPA) model was employed to construct a prognostic model for risk stratification. Progression-free survival (PFS) differences between MLRT and non-MLRT groups were compared across risk strata. MLRT recipients demonstrated superior median PFS (not reached vs. 34.87 months, p = 0.006). The RPA model classified patients into three risk groups based on the number of metastatic lesions, liver metastasis, and post-treatment Epstein-Barr Virus (EBV) DNA. The 3-year PFS rates for the low-, medium-, and high-risk groups were 71.4 %, 39.2 %, and 12.3 %. MLRT significantly improved 3-year PFS in low-risk patients (82.8 % vs. 69.1 %, p = 0.031), but not in medium or high-risk groups. Independent adverse prognostic factors included detectable post-treatment EBV DNA (HR = 3.36), liver metastasis (HR = 1.5), and >5 metastatic lesions (HR = 1.52). MLRT benefits dmNPC patients with low-risk features (limited metastases, undetectable EBV DNA). Risk stratification using metastatic burden and EBV DNA status may guide personalized MLRT decisions in the immunotherapy era.