Dysphagia and related toxicity in patients with head and neck cancer receiving helical intensity modulated radiotherapy +/- chemotherapy: Implications for speech pathology management

Abstract

The management of head and neck cancer (HNC) using radiotherapy +/- chemotherapy (C)RT is associated with significant morbidity, due to key structures required for speech, swallowing, respiration, and voice falling within the treatment field. Common sequelae of non-surgical treatment include a wide range of toxicities, though dysphagia (swallowing difficulty) is particularly prominent. Dysphagia may be a short-term acute toxicity, or persist long-term, and can have a significant negative impact on quality of life. With recent advancements in technology, new conformal radiotherapy techniques such as helical intensity modulated radiotherapy (H-IMRT) have been introduced into clinical practice. Such techniques offer potential to limit the radiation exposure to non-cancerous normal tissues, and potentially reduce associated treatment toxicities - whilst maintaining cure rates. However as yet, there is limited literature documenting the incidence, severity, and pattern of treatment related toxicities, including dysphagia, associated with H-IMRT +/- chemotherapy, to support if such improvements for the patient are realised. Understanding how patients are impacted by new treatment approaches is crucial information for speech pathology services, that manage the dysphagia and related toxicities of patients. Therefore, the overall objective of this thesis was to evaluate the incidence and severity of dysphagia and related toxicities of patients undergoing H-IMRT +/- chemotherapy to inform speech pathology management practices. A secondary objective was to use this information to develop, and then evaluate a new clinical pathway of care. These objectives were addressed in a series of 4 studies.Study 1 (Chapter 2) prospectively examined the range of dysphagia and related toxicities from baseline to 12 weeks post H-IMRT +/- chemotherapy for a heterogeneous cohort of patients with mixed tumour sites and stages. A high proportion of patients were found to continue to experience grade 2-3 toxicity that peaked in the final week of treatment. Symptoms consistently improved thereafter, with the majority better than baseline by 12 weeks post-treatment. Concurrent chemotherapy at least doubled the odds of experiencing most symptoms. The findings of Chapter 2 confirmed that despite advancements in radiotherapy technique, patients continue to require speech pathology supportive care, particularly in the final weeks of treatment and the acute period post-treatment. In contrast to the heterogeneous cohort examined in Chapter 2, Chapter 3 examined the clinical outcomes of a “high-risk” subgroup, including patients with oropharyngeal squamous cell carcinoma (OPSCC) receiving H-IMRT with concurrent chemotherapy. A high proportion of patients experienced grade 3 dysphagia with comparable or lower incidence of most other toxicities compared with traditional IMRT. Symptoms peaked in the final week of treatment and improved thereafter. However, most symptoms had not returned to baseline by 12 weeks post-treatment. Grade 3 dysphagia was twice as common for patients with T3-4 tumours compared to T2 tumours. The findings of Chapter 3 confirm the OPSCC patient group continue to be at “high risk” for dysphagia despite advances in conformal radiotherapy and should be prioritised for intensive speech pathology support.In Chapter 4, further tumour subsite analysis sought to address the gap in the literature by prospectively documenting the toxicity outcomes of a subgroup of patients anecdotally considered “low risk” for dysphagia - those patients with parotid tumours and cutaneous HNC receiving H-IMRT or 3D conformal radiation therapy (3DCRT). Findings confirmed that a very low proportion of patients experienced dysphagia or related toxicity requiring speech pathology support. If present, symptoms peaked in week 5 of treatment and resolved rapidly. The findings of Chapter 4 confirm this patient group is indeed at “low risk” for dysphagia and related toxicities during radiation treatment and represent a subgroup likely amenable to an alternative service delivery model.Utilising the results from studies reported in Chapters 2-4, Chapter 5 examined an alternative service delivery model for patients at low dysphagia risk. That study prospectively evaluated the implementation, clinical safety, cost analysis, and service efficiency of a new interdisciplinary service delivery model (The Pathway) of primary dietetic management using dysphagia screening with rapid access to speech pathology when required. Results suggest The Pathway is a safe and effective method of managing this subgroup of “low risk” patients during radiotherapy treatment. Patients experienced a reduction in hospital appointments, creating direct benefit for the health service through resource recovery - facilitating reallocation of speech pathology services to the “high risk” patients identified in Chapter 3. The findings, clinical implications, limitations, and future areas of research are discussed in Chapter 6 of this thesis. In conclusion, this thesis provides information detailing the incidence, severity, and temporal pattern of dysphagia and related toxicities experienced by patients with HNC undergoing H-IMRT +/- chemotherapy to optimise supportive care and enhance patient education. These findings can be used to inform the timing and intensity of patient centred speech pathology service delivery models that meet the specific needs of patient subgroups and can form the basis of future guidelines for speech pathology support.