Dysphagia at 1 Year is Associated With Mean Dose to the Inferior Section of the Brain Stem.

PURPOSE: Dysphagia is a common toxicity after head and neck (HN) radiation therapy that negatively affects quality of life. We explored the relationship between radiation therapy dose to normal HN structures and dysphagia 1 year after treatment using image-based datamining (IBDM), a voxel-based analysis technique. METHODS AND MATERIALS: We used data from 104 patients with oropharyngeal cancer treated with definitive (chemo)radiation therapy. Swallow function was assessed pretreatment and 1 year posttreatment using 3 validated measures: MD Anderson Dysphagia Inventory (MDADI), performance status scale for normalcy of diet (PSS-HN), and water swallowing test (WST). For IBDM, we spatially normalized all patients' planning dose matrices to 3 reference anatomies. Regions where the dose was associated with dysphagia measures at 1 year were found by performing voxel-wise statistics and permutation testing. Clinical factors, treatment variables, and pretreatment measures were used in multivariable analysis to predict each dysphagia measure at 1 year. Clinical baseline models were found using backward stepwise selection. Improvement in model discrimination after adding the mean dose to the identified region was quantified using the Akaike information criterion. We also compared the prediction performance of the identified region with a well-established association: mean doses to the pharyngeal constrictor muscles. RESULTS: IBDM revealed highly significant associations between dose to distinct regions and the 3 outcomes. These regions overlapped around the inferior section of the brain stem. All clinical models were significantly improved by including mean dose to the overlap region (P ≤ .006). Including pharyngeal dosimetry significantly improved WST (P = .04) but not PSS-HN or MDADI (P ≥ .06). CONCLUSIONS: In this hypothesis-generating study, we found that mean dose to the inferior section of the brain stem is strongly associated with dysphagia 1 year posttreatment. The identified region includes the swallowing centers in the medulla oblongata, providing a possible mechanistic explanation. Further work including validation in an independent cohort is required.

Development of the remote 100 ml water swallow test versus clinical assessment in patients with head and neck cancer: Do they agree?

BACKGROUND: The 100 ml water swallow test (WST) is a validated swallow assessment used in head and neck cancer (HNC). We aimed to determine the level of agreement when completing the 100 ml WST via clinician-graded video-testing or patient self-testing compared to standard face-to-face assessment (FTF). METHODS: Convenience sampling from four UK centers. INCLUSION CRITERIA: patients with HNC treated with any modality prior to, or within 5 years of treatment. Participants were recruited to complete the 100 ml WST by video-testing or self-testing and compared with FTF. RESULTS: Sixty-three patients were recruited; 1 was unable to perform the task; 30 in video-testing; and 32 in self-testing. There was no difference in swallow capacity (p = 0.424) and volume (p = 0.363) for the video-testing or the self-testing swallow capacity (p = 0.777) and volume (p = 0.445). CONCLUSIONS: This study demonstrates that video-testing and self-testing are reliable methods of completing the 100 ml WST for this sample of patients with HNC.