CROSSROAD: Treatment Regimen Switch - Re-induction Chemotherapy vs. Direct Radiotherapy in LANPC With Inadequate Response to Induction Chemotherapy

Inclusion Criteria: Age: 18 to 70 years old. Histologically confirmed non-keratinizing nasopharyngeal carcinoma (WHO Type II/III). Initial treatment with no distant metastasis: Locally advanced nasopharyngeal carcinoma (according to the AJCC/UICC 9th edition staging, stage II-III, i.e., T3-4N0-3M0 or T1-2N2-3M0). Completion of two cycles of standard induction chemotherapy (such as TPF, GP, TP, etc.). Post-induction chemotherapy evaluation: Disease stability (SD) or disease progression (PD) after two cycles of induction chemotherapy, as assessed by RECIST 1.1 criteria, based on enhanced MRI of the nasopharynx. ECOG Performance Status (PS): 0-1. Bone marrow, liver, and kidney function: Sufficient to tolerate concurrent chemoradiotherapy (specific criteria to be referenced). Informed consent: Voluntary participation in the study and signing of written informed consent. Exclusion Criteria: History of head and neck tumor radiotherapy or any other malignant cancer history (except for cured non-melanoma skin cancer). Partial response (PR) or complete response (CR) after induction chemotherapy. Severe uncontrolled comorbidities, such as unstable angina, congestive heart failure, severe chronic obstructive pulmonary disease (COPD), or uncontrolled diabetes mellitus. Active infection or severe immunodeficiency diseases. Pregnant or breastfeeding women. Any mental or social disorders that may interfere with study evaluation or compliance. Other conditions deemed by the investigator to be unsuitable for participation in the study.