Real-World RAIRI-Guided Risk Stratification for Adjuvant Therapy Benefit After Chemoradiotherapy in NPC

This prospective, multicenter, real-world observational study aims to evaluate whether a response-adapted individualized risk index, the RAIRI model, can identify patients with non-metastatic nasopharyngeal carcinoma who may or may not benefit from adjuvant therapy after standard chemoradiotherapy. Patients will receive standard treatment according to routine clinical practice. After completion of chemoradiotherapy and assessment at approximately 1 month after radiotherapy, longitudinal multimodal response data, including plasma cfEBV DNA dynamics and MRI-based tumor response, will be incorporated into the RAIRI model to estimate the predicted 5-year progression-free survival. Patients will be stratified into a RAIRI low-risk group, defined as predicted 5-year PFS ≥85%, and a RAIRI high-risk group, defined as predicted 5-year PFS \<85%. Within each RAIRI risk stratum, outcomes will be compared between patients who receive adjuvant systemic therapy, mainly PD-1 inhibitor-based adjuvant immunotherapy, and those who undergo routine surveillance without adjuvant systemic therapy. The primary endpoint is 3-year failure-free survival. Secondary endpoints include overall survival, locoregional relapse-free survival, distant metastasis-free survival, complete response rate after chemoradiotherapy, distribution of RAIRI risk groups, adverse events, late toxicities, and longitudinal health-related quality of life.