Dosimetric Predictors of Patient-Reported Xerostomia and Dysphagia With Deintensified Chemoradiation Therapy for HPV-Associated Oropharyngeal Squamous Cell Carcinoma.

PURPOSE/OBJECTIVE(S): To estimate the association between different dose-volume metrics of the salivary glands and pharyngeal constrictors with patient reported severity of xerostomia/dysphagia in the setting of deintensified chemoradiation therapy (CRT). METHODS AND MATERIALS: Forty-five patients were treated on a phase 2 study assessing the efficacy of deintensified CRT for favorable-risk, HPV-associated oropharyngeal squamous cell carcinoma. Patients received 60 Gy intensity modulated radiation therapy with concurrent weekly cisplatin (30 mg/m2), and reported the severity of their xerostomia/dysphagia (before and after treatment) using the patient-reported outcome version of the Common Terminology Criteria for Adverse Events (CTCAE) (PRO-CTCAE). Individual patient dosimetric data of the contralateral parotid and submandibular glands and pharyngeal constrictors were correlated with changes in PRO-CTCAE severity. A change in severity (from baseline) of ≥2 was considered clinically meaningful. Associations between dose-volume metrics and patient outcomes were assessed with receiver operating characteristic (ROC) curve and logistic regression model. RESULTS: Six months after CRT, patients reporting <2 change in xerostomia severity (n=14) had an average Dmean = 22 ± 9 Gy to the sum of the contralateral glands (parotid + submandibular) compared with the patients reporting ≥2 change (n=21), who had an average Dmean = 34 ± 8 Gy. V15 to V55 for the combined contralateral glands showed the strongest association with xerostomia (area under the curve [AUC] = 0.83-0.86). Based on the regression analysis, a 20% risk of toxicity was associated with V15 = 48%, V25 = 30%, and Dmean=21 Gy. Six months after CRT, patients reporting <2 change in dysphagia severity (n=26) had an average V55 = 76 ± 13 (%) to the superior pharyngeal constrictor compared with the patients reporting ≥2 change in severity (n=9), who had average V55 = 89 ± 13 (%). V55to V60 had the strongest association with dysphagia (AUC = 0.70-0.75). Based on the regression analysis, a 20% risk of toxicity was associated with V55 = 78%, V60 = 40%. The findings at 12 months were similar. CONCLUSIONS: After deintensified CRT, the rate of patient-reported xerostomia/dysphagia appears to be associated with the V15 of the combined contralateral salivary glands and V55 to V60 of the superior pharyngeal constrictors.

Duke Scholars

Author Shiva Kumar Das Radiation Oncology