Can IMRT or Brachytherapy Reduce Dysphagia Associated With Chemoradiotherapy of Head and Neck Cancer? The Michigan and Rotterdam Experiences

Abstract

Purpose-Dysphagia is a major late complication of intensive chemoradiotherapy of head and neck cancer. The initial clinical results of intensity-modulated radiotherapy (IMRT), or brachytherapy, planned specifically to reduce dysphagia are presented.Patients and Methods-Previous research at Michigan University has suggested that the pharyngeal constrictors and glottic and supraglottic larynx are likely structures whose damage by chemo-RT causes dysphagia and aspiration. In a prospective Michigan trial, 36 patients with oropharyngeal (n = 31) or nasopharyngeal (n = 5) cancer underwent chemo-IMRT. IMRT cost functions included sparing noninvolved pharyngeal constrictors and the glottic and supraglottic larynx. After a review of published studies, the retropharyngeal nodes at risk were defined as the lateral, but not the medial, retropharyngeal nodes, which facilitated sparing of the swallowing structures. In Rotterdam, 77 patients with oropharyngeal cancer were treated with IMRT, three dimensional RT, or conventional RT; also one-half received brachytherapy. The dysphagia endpoints included videofluoroscopy and observer-assessed scores at Michigan and patient-reported qualityof-life instruments in both studies.Results-In both studies, the doses to the upper and middle constrictors correlated highly with the dysphagia endpoints. In addition, doses to the glottic and supraglottic larynx were significant in the Michigan series. In the Rotterdam series, brachytherapy (which reduced the doses to the swallowing structures) was the only significant factor on multivariate analysis. Conclusion-The dose-response relationships for the swallowing structures found in these studies suggest that reducing their doses, using either IMRT aimed at their sparing, or brachytherapy, might achieve clinical gains in dysphagia.

Dysphagia in Head and Neck Cancer Patients Treated with Chemoradiotherapy

“…3). IMRT can be used to reduce the doses to DARS by applying dose constraints to them in an attempt to decrease dysphagia [74,77,78]. Numerous retrospective studies show a correlation between either subjective or objective assessment of dysphagia and dose volume parameters of anatomic swallowing structures (Table 7).…”

“…Numerous retrospective studies show a correlation between either subjective or objective assessment of dysphagia and dose volume parameters of anatomic swallowing structures (Table 7). These correlations suggest the reduction of the mean doses and the volumes of the DARS structures that receive 50 Gy or more (V50) in an attempt to reduce swallowing difficulties [51,68,[76][77][78]. Partial sparing of the pharyngeal constrictors is expected to confer a benefit if primary distal motor or sensory neural deficits and primary muscle dysfunction play a role in dysphagia [56].…”

Volumetric modulated arc therapy (VMAT) and simultaneous integrated boost in head-and-neck cancer: is there a place for critical swallowing structures dose sparing?

“…The most predictive dosimetric indices for the PCMs were found to be the mean dose [14][15][16][17][18][19] and the volume receiving more than 60 Gy 14,18 and 65 Gy 14,31 in the uPCM. Similarly, the most predictive dosimetric indices for the SGL were the mean dose 17,20 and the volume receiving .50 Gy.…”

“…13 Several clinical trials have analysed the relationship between the irradiated tissues and dysphagia assessing consistent data for the crucial structures related to swallowing dysfunction. [14][15][16][17][18][19][20] In particular, pharyngeal constrictors muscles (PCM) and the glottic/supraglottic larynx (SGL) have been identified as principal organs in which dysfunction after chemoradiation causes dysphagia and aspiration. 21 The common findings of these studies were that increased radiation dose to these structures resulted in higher level of dysphagia, all demonstrating a significant correlation between dysphagia/aspiration and the mean doses to PCM and SGL.…”

Oropharyngeal Cancer

“…If altered fractionation is selected, the limitations associated with the combination use of chemotherapy should be considered (which is described later). Brachytherapy [ 34 ] and stereotactic radiosurgery [ 35 ] are considered better options for minimizing the radiation dose to normal organs such as the parotid gland, mandibula, and pharyngeal constrictor muscle.…”