Addition of S-1 to radiotherapy for treatment of T2N0 glottic cancer: Results of the multiple-center retrospective cohort study in Japan with a propensity score analysis

Objectives: This multicenter retrospective cohort study aimed to evaluate the significance of adding S-1 to radiotherapy (RT) for the treatment of T2N0 glottic cancer using a propensity score matched analysis in Japan.

Materials and methods: This study was conducted on 287 patients with T2N0 glottic cancer who were treated with definitive RT or chemoradiotherapy with S-1 (S-1 RT) between April 2007 and March 2017. Propensity score matched analysis was performed to ensure the well-balanced characteristics of the groups of patients who received RT alone and S-1 RT. Overall, progression-free and laryngectomy-free survivals and local control and laryngeal preservation rates were compared.

Results: Fifty-four pairs of patients were selected after performing propensity score matched analysis. Clinical characteristics were well-balanced between the two groups. The overall survival of patients in the S-1 RT group was significantly better than those in the RT alone group (P = 0.008). The progression-free and laryngectomy-free survivals of patients in the S-1 RT group were also better than those in the RT alone group; however, the differences were not significant. In contrast, patients in the S-1 RT group had slightly lower local control and laryngeal preservation rates compared with those in the RT alone group. The incidence of dermatitis in the S-1 RT group was significantly higher than that in the RT alone group in the matched population (P = 0.013).

Conclusions: The addition of S-1 to RT for the treatment of T2N0 glottic cancer was not associated with better local control and laryngeal preservation rates in this study.