Induction Chemotherapy Followed by Radiotherapy vs Chemoradiotherapy in Nasopharyngeal Carcinoma

Importance: Induction chemotherapy plus concurrent chemoradiotherapy is recommended for locoregionally advanced nasopharyngeal carcinoma but is associated with higher rates of acute toxic effects and low compliance. Evidence on de-escalating treatment intensity after induction chemotherapy is limited. Objective: To assess if radiotherapy was noninferior to chemoradiotherapy after induction chemotherapy for locoregionally advanced nasopharyngeal carcinoma. Design, Setting, and Participants: From April 2015 to March 2018, a multicenter, open-label, randomized, noninferiority, phase 3 trial was conducted at 5 Chinese hospitals. A total of 383 patients aged 18 to 70 years with an untreated histologically confirmed nonkeratinizing tumor, Karnofsky performance status score not worse than 70, proper organ function, and stage III to IVB nasopharyngeal cancer were enrolled. Data were analyzed from April 2023 to June 2023. Interventions: Patients were assigned randomly. Both groups received 3 cycles of induction chemotherapy consisting of intravenous administration (on day 1) of cisplatin at 60 mg/m2 and docetaxel at 60 mg/m2 and continuous intravenous infusion (from day 1 to day 5) of daily fluorouracil (600 mg/m2), repeated every 21 days. Subsequently, the patients received radiotherapy alone (induction chemotherapy in combination with radiotherapy [IC-RT] group) or concomitant cisplatin (30 mg/m2/week) with radiotherapy for 6 to 7 weeks (induction chemotherapy combined with chemoradiotherapy [IC-CCRT] group). Main Outcomes and Measures: The primary end point was 3-year progression-free survival (time from the initiation of therapy until the first indication of disease progression or death), with a noninferiority margin of 10%. The secondary end points included overall survival, locoregional failure-free survival, distant metastasis-free survival, response rate, and toxic effects. Results: A total of 383 patients (median [range] age, 48 [19-70] years; 100 women [26%]). Median follow-up time was 76 months (IQR, 70-89 months). The 3-year progression-free survival was 76.2% and 76.8% in the IC-RT (n = 193) and IC-CCRT groups (n = 190), respectively, in the intention-to-treat population, showing a difference of 0.6% (95% CI, -7.9% to 9.1%; P = .01 for noninferiority). Identical outcomes were reported in the per-protocol population. The incidence of grade 3 to 4 short-term toxic effects in the IC-RT group was less than the IC-CCRT group. No differences were observed in late toxic effects. Conclusions and Relevance: The results of this randomized clinical trial suggest that after induction chemotherapy for locoregionally advanced nasopharyngeal carcinoma, radiotherapy alone was noninferior to chemoradiotherapy in terms of 3-year progression-free survival. Trial Registration: ClinicalTrials.gov Identifier: NCT02434614.