• Non-functional larynx (NFL) was found to affect 30.9 % of patients with locally advanced laryngeal cancer who underwent curative non-surgical laryngeal preservation treatment for stage III/IV disease • The key measures of NFL were long-term gastrostomy and tracheostomy dependence, functional laryngectomy and chronic aspiration. • Multivariate analyses identified current smoking to be associated with 6.8-fold increase in NFL • Patients with pre-treatment hemi-laryngeal fixation were 3.4 times more likely to experience locoregional recurrence.