Dosimetric Parameters Correlate with Taste Alterations in Head and Neck Radiotherapy.

PURPOSE/OBJECTIVE(S): Dysgeusia is an acute and chronic side effect of head and neck chemoradiation, with persistent taste dysfunction 1-2 years post radiotherapy occurring in 23-50% of patients. Several head and neck clinical trials set oral cavity mean doses between 30 to 40 Gy, however, there are no set guidelines accurately defining the composite structure and anatomic boundaries for the oral cavity or separating the tongue into specific quadrants. In this single institution cross sectional study, we sought to determine the effects of radiation doses to specific regions of the oral cavity and tongue on patient-reported long term dysgeusia. We hypothesize that radiation Dose to specific structures in the oral cavity will correlate with long-term dysgeusia in patients who have received head and neck radiotherapy.

MATERIALS/METHODS: Patients with primary head and neck cancer receiving definitive intensity modulated radiation therapy (RT) completed quality of life assessments that included patient-reported gustatory function, 1 year post RT. Dosimetric data from RT plans were collected for specific regions and organs at risk within the oral cavity. These structures included the anterior, posterior, superior and inferior tongue (OT), pharyngeal constrictors (as a surrogate for the corda-tympani) and the oral cavity. A forward binary logistic regression model was performed using these data points with scoring from the QLQ-H&N43 questionnaire subsection on taste (Q45) to determine the most predictive values for dysgeusia and the OR for moderate/severe alterations in taste.

RESULTS: A total of 78 patients were included in this study, of these patients, 63 had dosimetric data for the pharyngeal constrictors. The Oral Cavity Volume percentage receiving 50Gy (OC V50) and Pharyngeal Constrictors Volume percentage receiving 55Gy (PC V55) were the most predictive constraints for dysgeusia. (0.042, p = 0.011 and 0.041, p = 0.033). Holding all other variables constant in a forward binary logistic regression including 78 patients, the odds of having moderate to severe taste alterations increased by 56% (OR 1.045, 95% CI 1.012-1.079) for a 1% increase in OCV50. When analyzing the 68 patients with available pharyngeal constrictors data, taste alteration increased 20% for every 1% increase in PCV55 (OR 1.042, 95% CI 1.003-1.082). There was no correlation with taste alterations in any of the dose parameters tested (Dmax, mean and V50 up to V70) for superior, inferior, anterior or posterior regions of the tongue.

CONCLUSION: Dosimetric parameters for the oral cavity (OC V50) and pharyngeal constrictors (PC V55) were positively correlated with taste alterations, however, no other specific regions within the oral tongue predicted taste disfunction. Normal tissue complication probability modeling curves to identify OC V50 and PC V55 constraints for dysgeusia are needed.