To evaluate the locoregional control, survival rate, toxicity, and quality of life in patients with nasopharyngeal carcinoma treated with reduced prophylactic irradiation doses to the Low-Risk Clinical Target Volume (CTV).

This phase 3, multicenter, non-inferiority, randomized controlled clinical trial recruits patients with newly diagnosed, untreated, non-distant metastatic, non-keratinizing nasopharyngeal carcinoma (NPC). The intervention involves comparing reduced-dose prophylactic irradiation to standard-dose prophylactic irradiation for the low-risk clinical target volume (CTV). The objective is to compare the locoregional control, survival rate, toxicity, and quality of life between the two groups.

Inclusion Criteria:

Newly diagnosed, untreated, non-distant metastatic, and non-keratinizing NPC; aged between 18 and 70 years; Eastern Cooperative Oncology Group performance score of 0-1; adequate hematologic function (neutrophil count ≥ 1.5 × 10^9/L, platelet count ≥100×109/L, and hemoglobin≥ 90 g/L); adequate renal function (creatinine ≤ 1.5 upper limit of normal [ULN]) or calculated creatinine clearance (CrCl) ≥ 60 mL/min (Cockcroft-Gault formula); and adequate hepatic function (serum bilirubin ≤ 2.0×ULN, and alanine aminotransferase and aspartate aminotransferase ≤ 2.5×ULN).

Exclusion Criteria:

Previous chemotherapy treatment, surgery (except diagnostic) or radiotherapy to the neck or nasopharyngeal regions; previous malignancy (except for cured basal cell carcinoma or carcinoma in situ of the cervix); lactation or pregnancy; or severe coexisting illness.

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