Dysphagia-optimised Intensity-modulated Radiotherapy Techniques in Pharyngeal Cancers: Is Anyone Going to Swallow it?

Abstract

Dysphagia after primary chemoradiotherapy or radiation alone in pharyngeal cancers can have a devastating impact on a patient's physical, social and emotional state. Establishing and validating efficient dysphagia-optimised radiotherapy techniques is, therefore, of paramount importance in an era where health-related quality of life measures are increasingly influential determinants of curative management strategies, particularly as the incidence of good prognosis, human papillomavirus-driven pharyngeal cancer in younger patients continues to rise. The preferential sparing achievable with intensity-modulated radiotherapy (IMRT) of key swallowing structures implicated in post-radiation dysfunction, such as the pharyngeal constrictor muscles (PCM), has generated significant research into toxicity-mitigating strategies. The lack of randomised evidence, however, means that there remains uncertainty about the true clinical benefits of the dosimetric gains offered by technological advances in radiotherapy. As a result, we feel that IMRT techniques that spare PCM cannot be incorporated into routine practice. In this review, we discuss the swallowing structures responsible for functional impairment, analyse the studies that have explored the dose-response relationship between these critical structures and late dysphagia, and consider the merits of reported dysphagia-optimised IMRT (Do-IMRT) approaches, thus far. Finally, we discuss the dysphagia/aspiration-related structures (DARS) study (ISRCTN 25458988), which is the first phase III randomised controlled trial designed to investigate the impact of swallow-sparing strategies on improving long-term function. To maximise patient benefits, improvements in radiation delivery will need to integrate with novel treatment paradigms and comprehensive rehabilitation strategies to eventually provide a patient-centric, personalised treatment plan.

The experiences of people who receive swallow therapy after surgical treatment of head and neck cancer

“…As the burden associated with reduced swallow and speech function has been recognised [6], research has begun to explore how particular oncological and surgical treatment interventions may reduce impact on function [7,8]. This has included reducing toxicity to structures involved in the mechanism of swallow [9], and surgical approaches to limit motor and sensory dysfunction [10]. Similarly, swallow research has explored ways rehabilitation interventions can improve swallow physiology, involving postural adaptations, techniques to improve swallow competence such as swallow manoeuvres by directing food or drink via intact musculature rather than anatomy that may have been altered by disease or surgery [11], respiratory swallowing coordination [12] and expiratory muscle strength training [13].…”

Systematic review and meta‐analysis of the impact of dosimetry to dysphagia and aspiration related structures

“…Previous systematic reviews have reported on the impact of dose to dysphagia and aspiration structures on dysphagia. This evidence is outdated due to new literature in this area.…”

“…While both 3D and intensitymodulated techniques define structures in 3D, the major differences are the degree of conformity, dose to normal tissue, and capability of IMRT to have dose variation within a field whereas 3D conformal within field dose is homogenous. 12 Previous systematic reviews [13][14][15][16][17][18] have reported on the impact of dose to dysphagia and aspiration structures on dysphagia. This evidence is outdated due to new literature in this area.…”

Assessing Novel Drugs and Radiation Technology in the Chemoradiation of Oropharyngeal Cancer

“…More recently research has centred on developing models to predict the swallowing function following radiotherapy [ 27 , 28 , 29 ]. The dependence of late swallowing function on various intuitive swallowing OARs, including the pharyngeal constrictor muscles and the potential for modest reductions in the incidence of late swallowing problems by reducing the dose to these structures, has been examined by modelling studies and is being examined in an ongoing randomised trial [ 10 , 30 ].…”