A Prospective, Randomized, Open-Label, Multicenter Phase III Clinical Study Comparing Intensity-Modulated Proton Therapy and Intensity-Modulated Photon Radiotherapy in Locally Advanced Nasopharyngeal Carcinoma

This is a multicenter, open-label, randomized Phase III clinical trial designed to compare the safety and efficacy of intensity-modulated proton therapy (IMPT) versus intensity-modulated photon radiotherapy (IMRT) in patients with newly diagnosed, high-risk, locoregionally advanced nasopharyngeal carcinoma.

Eligible patients are adults aged 18 to 70 years with histologically confirmed non-keratinizing nasopharyngeal carcinoma (WHO type II or III) and clinical stage T4 or N3 disease without distant metastasis (M0), according to the AJCC staging system.

All enrolled patients will receive three cycles of induction chemotherapy consisting of gemcitabine plus cisplatin. This will be followed by concurrent chemoradiotherapy combined with immunotherapy. During the concurrent treatment phase, patients will be randomized in a 1:1 ratio to receive either IMPT or IMRT, delivered according to protocol-defined target delineation, dose prescription, and fractionation schedules.

The first primary endpoint is the incidence of grade ≥3 acute treatment-related toxicities, defined as treatment-related adverse events of grade 3 or higher occurring from the initiation of radiotherapy to 90 days after completion of radiotherapy. Toxicities will be graded according to CTCAE version 5.0 and RTOG criteria. Ototoxicity, including hearing loss or tinnitus, will be further evaluated using the ASHA (1994) significant change criteria for pure-tone audiometry.The second primary endpoint is the 3-year progression-free survival (PFS) rate, defined as the proportion of patients who remain alive without documented disease progression within 3 years after randomization. Disease progression is defined as locoregional recurrence, distant metastasis, or death from any cause, whichever occurs first.

Secondary endpoints include overall survival (OS), defined as the time from randomization to death from any cause; locoregional relapse-free survival (LRRFS), defined as the time from enrollment to the first occurrence of locoregional recurrence; distant metastasis-free survival (DMFS), defined as the time from randomization to the first occurrence of distant metastasis; objective response rate (ORR), defined as the proportion of patients achieving complete response (CR) or partial response (PR), assessed at 2 weeks after completion of induction chemotherapy and at 3 months after completion of radiotherapy; incidence of grade <3 acute toxicities; and incidence and severity of late treatment-related toxicities assessed according to CTCAE version 5.0.Quality of life will be evaluated using the European Organisation for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire Core 30 (QLQ-C30, version 3.0) and the Head and Neck Cancer-specific module QLQ-H&N35 (version 1.0), administered at baseline, at the end of treatment, and during follow-up visits.

The trial aims to determine whether IMPT can reduce treatment-related toxicities while maintaining or improving disease control and survival outcomes compared with IMRT.