Prognostic value of the cervical lymph node necrosis ratio in nasopharyngeal carcinoma

•Cervical lymph nodal necrosis (CNN) was an independent risk factor for treatment sensitivity and prognosis of nasopharyngeal carcinoma (NPC).•Increasing the chemotherapy cycle can improve overall survival (OS) and distant metastasis‐free survival (DMFS) in patients with lower CNN ratio.•The treatment planning system (TPS) was used to delineate the volume of metastatic lymph nodes and the necrotic area of lymph nodes on magnetic resonance images (MRI), and calculate the corresponding necrotic proportion.•Our study not only carried out qualitative analysis but also quantitative analysis of CNN in NPC. Whether cervical lymph node necrosis (CNN) is an independent adverse prognostic factor in nasopharyngeal carcinoma (NPC) has not been determined. In this study, the CNN ratio was graded quantitatively to explore the prognostic value in NPC. We retrospectively reviewed a total of 648 pathologically confirmed as NPC. We outlined metastatic lymph nodes and necrotic area of lymph nodes slice by slice on the magneticresonanceimages (MRI) cross section, and calculated the corresponding CNN ratio. The median CNN ratio (17.37 %) was taken as the cut-off point, 256 (39.51 %) patients were divided into CNN1 group (