Introduction

Nasopharyngeal carcinoma (NPC) demonstrates a pronounced ethnic and geographical distribution, characterized by significantly elevated incidence rates in Southern China, Southeast Asia, and the Middle East/North Africa regions.1,2,3 Within these regions, Fujian Province in Southern China is particularly affected. The etiology of NPC is complex, involving a multifactorial interplay of genetic predisposition, viral infections—primarily Epstein-Barr virus (EBV)—and various environmental factors, all of which are crucial to its pathogenesis.4,5,6 Despite significant advances in diagnostic and therapeutic methods, NPC remains a formidable challenge due to its unique anatomical location, early tendency for lymphatic metastasis, and proclivity for distant dissemination.

Radical radiotherapy (RT) is the standard treatment for early-stage NPC and a key component of the multidisciplinary management of locally advanced cases.7,8,9 Compared to traditional two-dimensional or three-dimensional radiation therapy, intensity-modulated radiotherapy (IMRT) delivers higher radiation doses more precisely to NPC while protecting adjacent critical structures and reducing treatment-related toxicity. IMRT enhances local control and survival rates in patients with NPC.10,11 However, its therapeutic effectiveness can be compromised by interruptions in the treatment schedule. These interruptions may result from equipment malfunctions, patient-related issues (e.g., RT intolerance or non-compliance), institutional factors (e.g., scheduling conflicts), or public holidays.12,13 The accelerated repopulation of tumor cells, particularly in rapidly proliferating tumors such as head and neck cancers, provides a radiobiological basis for the poor prognosis associated with extended treatment durations.14,15

Research has investigated radiotherapy interruptions (RTIs) in various tumors, including lung, breast, and anal squamous cell carcinoma, revealing a correlation between RTIs and unfavorable survival outcomes.16,17,18 For instance, prolonged RT has been associated with reduced overall survival (OS) in patients with stage III non-small cell lung cancer undergoing concurrent chemoradiotherapy (CCRT).9 Similarly, Yao et al. found that RTIs exceeding five days negatively impacted the prognosis of patients with stage T3-T4 NPC.19 Despite these findings, the precise influence of RTIs on survival outcomes in patients with NPC receiving IMRT therapy is still insufficiently examined. Additionally, research on the critical thresholds at which RTIs become detrimental to survival is inconsistent. In the context where IMRT has been widely applied in the treatment of NPC, more data are necessary to establish definitive RTI thresholds that could inform treatment strategies and improve patient outcomes.

Therefore, within the current backdrop, an in-depth evaluation of the impact of RTI on survival outcomes in patients with NPC receiving IMRT holds significant clinical importance for optimizing clinical RT protocols and enhancing patients’ quality of life. This study aims to conduct a comprehensive retrospective analysis of patients with NPC receiving IMRT, focusing on assessing the impact of RTI on survival outcomes, and to further compare the differences between continuous and interrupted RT on patient survival prognosis, in order to provide evidence-based support for developing more precise treatment implementation strategies in clinical practice.