Late radiation-associated dysphagia following treatment for head and neck cancer: a scoping review

To provide an overview of existing literature reporting swallowing outcomes beyond two years post- head and neck cancer treatment. Objectives were to establish prevalence of late radiation-associated dysphagia (-RAD); identify risk factors of developing late-RAD and synthesise the dysphagia findings reported.

The PRISMA-ScR checklist for conducting scoping reviews was adopted. Searches of PubMed, EMBASE, Scopus, CINAHL, Web of Science, OpenGrey, Google Scholar and Google Advanced were completed by December 2022. Eligibility criteria included studies written in English from 1996 reporting swallowing outcomes from 2 years or more post-treatment. Data was extracted from included studies, tabulated, synthesised and reported as categories.

Screening 7671 studies resulted in 39 studies included in the review. There was wide variation in dysphagia outcome measures used and timing of collection across studies. Prevalence could not be established. All studies reported a degree of impairment in at least one measure in a proportion of patients. Numerous risk factors were identified (including tumour site, and T-classification, age, radiotherapy dose), but there were conflicting findings and meaningful synthesis was challenging. Characteristics of late-RAD included high aspiration rates; reduced efficiency of swallowing and lower cranial neuropathy.

Significant gaps exist in the evidence base regarding late-RAD such as who is affected, why and what the trajectory of decline will be. Swallowing safety is often compromised. A consensus on the definition of late-RAD is needed along with increased uniformity in collection of outcome measures, in order to improve understanding and guide future research and service delivery models.