Predicting the severity and prognosis of trismus after intensity-modulated radiation therapy for oral cancer patients by magnetic resonance imaging

PLoS One. 2014 Mar 21;9(3):e92561. doi: 10.1371/journal.pone.0092561. eCollection 2014.

Abstract

To develop magnetic resonance imaging (MRI) indicators to predict trismus outcome for post-operative oral cavity cancer patients who received adjuvant intensity-modulated radiation therapy (IMRT), 22 patients with oral cancer treated with IMRT were studied over a two-year period. Signal abnormality scores (SA scores) were computed from Likert-type ratings of the abnormalities of nine masticator structures and compared with the Mann-Whitney U-test and Kruskal-Wallis one-way ANOVA test between groups. Seventeen patients (77.3%) experienced different degrees of trismus during the two-year follow-up period. The SA score correlated with the trismus grade (r = 0.52, p<0.005). Patients having progressive trismus had higher mean doses of radiation to multiple structures, including the masticator and lateral pterygoid muscles, and the parotid gland (p<0.05). In addition, this group also had higher SA-masticator muscle dose product at 6 months and SA scores at 12 months (p<0.05). At the optimum cut-off points of 0.38 for the propensity score, the sensitivity was 100% and the specificity was 93% for predicting the prognosis of the trismus patients. The SA score, as determined using MRI, can reflect the radiation injury and correlate to trismus severity. Together with the radiation dose, it could serve as a useful biomarker to predict the outcome and guide the management of trismus following radiation therapy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carcinoma, Squamous Cell / radiotherapy*
  • Dose-Response Relationship, Radiation
  • Humans
  • Magnetic Resonance Imaging / methods
  • Masticatory Muscles / pathology
  • Masticatory Muscles / radiation effects
  • Mouth Neoplasms / radiotherapy*
  • Prognosis
  • Radiation Injuries / etiology
  • Radiotherapy, Intensity-Modulated / adverse effects
  • Radiotherapy, Intensity-Modulated / methods
  • Retrospective Studies
  • Trismus / etiology*

Grants and funding

This work was supported by the Far Eastern Memorial Hospital grants (FEMH-2012-C-055; FEMH 101-2314-B-418-010-MY3). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.