Maximum incisal opening, caries experience and health-related quality of life in patients undergoing treatment for head and neck cancer – A longitudinal cohort study.

Abstract Purpose Prospective evaluation of the change in maximum incisal opening (MIO) in patients receiving treatment for head neck cancer (HNC), and its interaction with clinical parameters such as tumor site/ sub-site and type of treatment received. Secondary aim was to ascertain the longitudinal change in dental caries experience and health-related quality of life (HRQoL) during the study period. Methods Seventy treatment-naïve patients undergoing treatment for squamous cell carcinoma (SCC) of oral cavity and/or oropharynx were assessed at 3 designated time-points; pre-treatment (T0), immediate post-treatment (T1) and 6-months post-treatment (T2). The primary study variable was change in MIO (cm) across 3 time points (T0, T1, T2). Dental caries incidence was measured using decayed, missing, filled teeth (DMFT) index and HRQoL was assessed using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaires (EORTC QLQ-C30 and H&N-35). Change in DMFT and HRQoL was assessed between T0 and T2. Non-parametric repeated measures ANOVA was used to analyse the longitudinal change in MIO and DMFT scores and their interaction with clinical parameters respectively. Wilcoxon signed-rank test was used to compare corresponding HRQoL domains between T0 and T2. All statistical tests were 2-sided, and differences with a p-value < 0.05 were considered statistically significant. Results Sixty-seven eligible HNC patients showed a significant change in mouth-opening and dental caries experience from T0 to T2, irrespective of tumor site/ sub-site and type of treatment (p < 0.001). Site-wise, patients with oral cavity cancer and specifically maxillary tumors; treatment-wise those undergoing surgery and/or, multi-modal treatment showed persistently reduced mouth opening late post-treatment. There was a statistical increase in head-and-neck site specific HRQoL symptoms at T2. A high prevalence (69%) of post-treatment trismus was noted especially in patients undergoing multi-modality treatment (83%). Conclusion Patients undergoing treatment for HNC demonstrate a significant longitudinal change in mouth-opening and caries incidence. They may show partial recovery of MIO at 6-months after an initial decrease in the immediate post-treatment period.