The standard treatment for postoperative high-risk locally advanced squamous cell carcinoma of the head and neck (LA-SCCHN) is chemoradiotherapy with 3-weekly cisplatin (100 mg/m). However, whether chemoradiotherapy with weekly cisplatin (40 mg/m) yields comparable efficacy with 3-weekly cisplatin in postoperative high-risk LA-SCCHN is unknown.

In this multi-institutional open-label phase II/III trial, patients with postoperative high-risk LA-SCCHN were randomly assigned to receive either chemoradiotherapy with 3-weekly cisplatin (100 mg/m) or with weekly cisplatin (40 mg/m) to confirm the noninferiority of weekly cisplatin. The primary end point of phase II was the proportion of treatment completion, and that of phase III was overall survival. A noninferiority margin of hazard ratio was set at 1.32.

Between October 2012 and December 2018, a total of 261 patients were enrolled (3-weekly cisplatin, 132 patients; weekly cisplatin, 129 patients). At the planned third interim analysis in the phase III part, after a median follow-up of 2.2 (interquartile range 1.19-3.56) years, chemoradiotherapy with weekly cisplatin was noninferior to 3-weekly cisplatin in terms of overall survival, with a hazard ratio of 0.69 (99.1% CI, 0.374 to 1.273 [< 1.32], one-sided for noninferiority = .0027 < .0043). Grade 3 or more neutropenia and infection were less frequent in the weekly arm (3-weekly weekly, 49% 35% and 12% 7%, respectively), as were renal impairment and hearing impairment. No treatment-related death was reported in the 3-weekly arm, and two (1.6%) in the weekly arm.

Chemoradiotherapy with weekly cisplatin is noninferior to 3-weekly cisplatin for patients with postoperative high-risk LA-SCCHN. These findings suggest that chemoradiotherapy with weekly cisplatin can be a possible treatment option for these patients.