Reduced mouth opening in patients with head and neck cancer treated with radiation therapy: an analysis of the Clinical Registry of Dental Outcomes in Head and Neck Cancer Patients (OraRad)

Objective. Trismus/reduced mouth opening (RMO) is a common side effect of radiotherapy (RT) for head and neck cancer (HNC). The objective was to measure RMO, identify risk factors for RMO, and determine its impact on quality of life (QOL). Study Design. OraRad is an observational, prospective, multicenter cohort study of patients receiving curative intent RT for HNC. Interincisal mouth opening measurements (n = 565) and patient-reported outcomes were recorded before RT and every 6 months for 2 years. Linear mixed-effects models were used to evaluate change in mouth opening and assess the relationship between trismus history and change in QOL measures. Results. Interincisal distance decreased from a mean (SE) of 45.1 (0.42) mm at baseline to 42.2 (0.44) at 6 months, with slight recovery at 18 months (43.3, 0.46 mm) but no additional improvement by 24 months. The odds of trismus (opening <35 mm) were significantly higher at 6 months (odds ratio [OR] = 2.21, 95% CI: 1.30 to 3.76) and 12 months (OR = 1.87, 95% CI: 1.08 to 3.25) compared with baseline. Females were more likely to experience trismus at baseline and during follow-up (P < .01). Patients with oral cavity cancer had the highest risk for trismus at baseline and post-RT (P < .01). RMO was associated with higher RT dose to the primary site and receiving concomitant chemotherapy (P < .01). Trismus was associated with self-reported difficulty opening the mouth and dry mouth (P < .01). Conclusions. A decrease in mouth opening is a common treatment-related toxicity after RT, with some recovery by 18 months. Trismus has a significant impact on survivor QOL. (Oral Surg Oral Med Oral Pathol Oral Radiol 2024;137:264-273)