This study is a multicenter, non-inferiority, open-label, randomized controlled Phase III clinical trial. It aims to compare the efficacy of modified delineation radiotherapy (experimental group) versus standard delineation radiotherapy (control group) in the prophylactic irradiation of neck lymphatic drainage areas III/IVa in nasopharyngeal carcinoma. The study evaluates the incidence of primary hypothyroidism, quality of life, and adverse events between the two groups.
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History of other malignant tumors (excluding basal cell carcinoma/squamous cell carcinoma of the skin or cervical carcinoma in situ);
History of radiotherapy (excluding radiotherapy outside the planned target area for conditions such as melanoma);
History of neck surgery;
Any severe comorbidities that may pose risks to the study or affect compliance, such as unstable heart disease requiring treatment, kidney disease, chronic hepatitis, poorly controlled diabetes (fasting blood glucose > 1.5 × ULN), or psychiatric disorders;