The association between initiation weekday of radiotherapy and local control in stage 1 glottic carcinoma: a retrospective analysis

Radiotherapy is one of the definitive treatments for head and neck squamous cell carcinoma, especially early-stage glottic squamous cell carcinoma. Although there are several studies on the initiation weekday of cancer treatment, there are very few studies in the radiotherapy field. Thus, the present study investigated whether the initiation weekday of radiotherapy affects the local control rate for stage 1 glottic squamous cell carcinoma. A total of 105 patients with stage 1 glottic squamous cell carcinoma underwent definitive radiotherapy alone between 2007 and 2021. The group in which radiotherapy was started between Monday and Wednesday was compared with the group in which radiotherapy was started on Thursday or Friday. Sixty-seven patients started radiotherapy between Monday and Wednesday and 38 on Thursday or Friday. The 5-year local control rate was 98% (95% confidence interval: 94-100%) in the Monday-Wednesday group and 83% (95% confidence interval: 71-96%) in the Thursday-Friday group, with a significant difference (P = 0.005). On multivariate analysis including age, overall administration time (days), fractionation, irradiation field size and initiation weekday of radiotherapy, no factors other than initiation weekday affecting local control were identified. Radiotherapy toxicity did not differ between the two groups. For stage 1 glottic squamous cell carcinoma, starting radiotherapy on Thursday or Friday is associated with a lower local control rate; therefore, radiotherapy should be started by Wednesday.