Oncological outcome of contralateral submental artery island flap versus primary closure in tongue squamous cell carcinoma: randomized non-inferiority clinical trial.

The aim of this study was to test the non-inferiority of the contralateral submental island flap (CSIF) compared with primary closure (PC) regarding local recurrence after partial glossectomy in patients with oral tongue squamous cell carcinoma (OTSCC). This open-label, non-inferiority randomized controlled trial enrolled patients with cT1-2 lateralized OTSCC. The primary outcome was local recurrence by 12 months postoperative. Non-inferiority would be declared if the upper limit of the two-sided 95% confidence interval (CI) for the proportion difference in local recurrence between the two groups did not exceed a non-inferiority margin of 15.0%. The functional outcome was assessed for superiority through secondary outcomes. In the intention-to-treat analysis, the local recurrence rate was 3.1% (1/32) in the CSIF group versus 9.4% (3/32) in the PC group; the proportion difference was - 6.3% (95% CI -18.0% to 5.5%). In the per-protocol analysis, the local recurrence rate was 3.1% (1/32) versus 3.3% (1/30); the proportion difference was - 0.2% (95% CI -9% to 8.6%). Speech was significantly superior in the CSIF group (P = 0.001). In conclusion, the CSIF was found to be non-inferior to PC regarding local recurrence at 1 year. A limitation of this study is the relatively large non-inferiority margin and consequently relatively small sample size. Further studies with a smaller non-inferiority margin and therefore larger sample size are needed to validate these findings.