Statistical analysis
The data analysis was conducted using SPSS, version 22.0 (Armonk, NY).
Exploratory binomial logistic univariate analyses were performed to
identify the potential predictors of NFL (age, smoking, T stage,
pre-treatment hemi-laryngeal fixation, pre-treatment gastrostomy,
chemoradiotherapy (CRT), pre-epiglottic tissue involvement,
pre-treatment tracheostomy, outer cartilage cortex breach). To account
for multicollinearity of the predictors, a multivariate binary logistic
(backward elimination) regression model was performed. Survival analyses
were conducted using the Kaplan-Meier curves. The Cox-proportional
hazard model was used to determine the significance of the individual
factors in predicting the locoregional recurrence. The significance
alpha level was set at p <0.05.