Concurrent chemoradiotherapy with 3-weekly versus weekly cisplatin in patients with locoregionally advanced nasopharyngeal carcinoma: A phase 3 multicentre randomised controlled trial (ChiCTR-TRC-12001979).

6006 Background: In intensity-modulated radiotherapy (IMRT) era, concurrent chemoradiotherapy (CCRT) with either every three week (ETW) or once a week (OAW) cisplatin is accepted practice for locoregionally advanced nasopharyngeal carcinoma (LANPC). However, ETW and OAW were never prospectively compared in phase 3 clinical trials. This study is to assess the efficacy and toxicity profiles of CCRT with ETW versus OAW schedule of cisplatin. Methods: We conducted an open-label phase 3 multicentre randomised controlled trial in an endemic area. Patients with stage II-IVB NPC were randomly assigned to receive either cisplatin 100 mg/m² every 3 weeks for 2 cycles or cisplatin 40 mg/m² weekly up to 6 cycles concurrently with IMRT. IMRT in both groups was given as 2.19-2.34 Gy per fraction with five daily fractions per week for 6-7 weeks to a total dose of 68-70 Gy to the primary tumor and 62-68 Gy to the involved neck area. The primary endpoint was failure-free survival. Intention-to-treat population was adopted for efficacy analyses. Results: Of the 526 eligible patients, 267 were assigned to OAW arm, and 259 to ETW arm. Two arms were well-balanced in all prognostic factors. No difference was observed in overall tumor response between OAW and ETW (99.6% vs 98.9%, P = 0.624). After a median follow-up of 17.5 months (range 1.6-64.1), estimated 2 year failure-free survival rate was 92% (95% CI 87.7-96.3) in OAW and 88.3% (95% CI 83.2-93.4) in ETW (hazard ratio 1.056, 95% CI 0.58-1.92). The grade 3 or 4 toxicities were similar between two arms, but leucopenia and thrombocytopenia were significantly higher in OAW compared with ETW (24.8% vs 15.9%, P = 0.015 and 5.2% vs 1.1%, P = 0.01, respectively). Stomatitis (35.2% vs 32.6%, P = 0.576), leucopenia and nausea/vomiting (11.2% vs 12.5%, P = 0.684) were the most commonly observed grade 3 or 4 toxicities during both OAW and ETW arms. Conclusions: Weekly regimen of cisplatin as CCRT shows similar treatment efficacy but increased toxic effect of leucopenia and thrombocytopenia compared with 3-weekly schedule in LANPC. Longer follow-up is needed to fully assess prognosis and late toxicities. Clinical trial information: ChiCTR-TRC-12001979.