Shrinking the Anterior Border of CTV2 for Nasopharyngeal Carcinoma to Reduce the Radiation of Nasal Cavity

This is a an open-label, non-inferiority, multicenter, randomized phase III trial aimed to explore the efficacy and safety of shrinking the anterior border of CTV2 in nasopharyngeal carcinoma patients without tumor invasion into the posterior nasal aperture. The enrolled patients will be 1:1 randomly assigned to receive reduced CTV delineation radiotherapy (anterior border of CTV2 defined as 5 mm anterior to the choanae), or standard CTV delineation radiotherapy (anterior border of CTV2 defined as the posterior 1/3 of the nasal cavity).

Inclusion criteria

• Newly diagnosed, histologically confirmed non-keratinizing carcinoma (WHO classification).
• Stage I-III disease (AJCC 9th edition).
• Tumor extends to nasal cavity (including nasal septum).
• No distant metastasis (M0).
• Age 18-70 years.
• Male or non-pregnant female.
• Scheduled for radiotherapy.
• ECOG performance status 0-1 .
• Adequate bone marrow function: white blood cells >4×10⁹/L, hemoglobin >90 g/L, platelets >100×10⁹/L.
• Normal hepatic/renal function: total bilirubin ≤1.5×ULN, AST/ALT ≤2.5×ULN, alkaline phosphatase ≤2.5×ULN, creatinine clearance ≥60 mL/min.
• Written informed consent obtained.

Exclusion criteria

• Keratinizing squamous cell carcinoma (WHO Type I) or basaloid squamous cell carcinoma.
• Age <18 or >70 years.
• Recurrent disease or distant metastasis.
• No tumor extension into the nasal cavity (including the nasal septum).
• Prior malignancy (except adequately treated basal/squamous cell skin cancer or cervical carcinoma in situ).
• Pregnancy/lactation (premenopausal women require pregnancy test; effective contraception mandated).
• Prior radiotherapy (except non-melanoma skin cancer with lesions outside current portals).
• Preoperative chemotherapy or surgical resection of primary/neck lesions (excluding diagnostic procedures).
• Severe coexisting illness.