Dose-volume analysis of radiation-induced trismus in head and neck cancer patients

Patient-, disease- and treatment-specific data were retrospectively recorded. Differences between groups were analyzed and mean absorbed dose to mastication structures was evaluated. Dosimetric comparisons were made between this study and our previous results.

Results: The prevalence of trismus was 24% at a median of 16 months after completion of radiotherapy. In bivariate analysis treatment technique (3DCRT vs. intensity modulated radiotherapy or helical tomotherapy), tumor site (oropharynx vs. other sites) and mean radiation doses to the ipsilateral lateral pterygoid muscle, the paired masseter muscles and the i MAS were significantly associated with MID ≤35 mm. In multivariable analysis only mean radiation dose to the i MAS was significantly associated to MID ≤35 mm.

Conclusion: Mean radiation dose to the ipsilateral masseter muscle is an important risk factor for trismus development. Dose reduction to this structure during radiotherapy should have a potential to diminish the prevalence of trismus in this patient group.