Dosimetric predictors of patient reported xerostomia and dysphagia with de-intensified chemoradiotherapy for HPV-associated oropharyngeal squamous cell carcinoma

Publication date: Available online 27 March 2017
Source:International Journal of Radiation Oncology*Biology*Physics
Author(s): Bhishamjit S. Chera, David Fried, Alex Price, Robert J. Amdur, William Mendenhall, Chiray Lu, Shiva Das, Nathan Sheets, Lawrence Marks, Panayiotis Mavroidis
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 de-intensified chemoradiotherapy (CRT).Methods and MaterialsForty-five patients were treated on a phase II study assessing the efficacy of de-intensified CRT for favorable risk, HPV-associated oropharyngeal squamous cell carcinoma. Patients received 60 Gy intensity modulated radiotherapy with concurrent weekly cisplatin (30 mg/m²), and reported severity of their xerostomia/dysphagia (pre- and post-treatment) using the patient reported outcome version of the 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.ResultsSix months post 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 to 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 (AUC = 0.83-0.86). Based on the regression analysis, a 20% risk of toxicity was associated with V15 = 48%, V25 = 30% and Dmean = 21Gy. 6 months post CRT, patients reporting < 2 change in dysphagia severity (N=26) had an average V55 = 76±13 (%) to the superior pharyngeal constrictor compared to the patients reporting ≥ 2 change in severity (N=9), who had average V55 = 89±13 (%). V55 - 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.ConclusionsFollowing de-intensified 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.

Teaser

The association of different dose/volume metrics of the salivary glands and pharyngeal constrictors to patient reported xerostomia/dysphagia was performed for patients treated with a de-intensified chemoradiotherapy regimen. In the setting of de-intensified chemoradiotherapy, the rate of patient reported xerostomia/dysphagia appears to associated with the V15 of the combined contralateral parotid and submandibular glands (a more stringent metric than what has been used with conventional doses) and V55 to V60 of superior pharyngeal constrictors.


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