Factors associated with acute and late dysphagia in the DAHANCA 6 & 7 randomized trial with accelerated radiotherapy for head and neck cancer

Background. Dysphagia is a common and debilitating side effect in head and neck radiotherapy (RT). Prognostic factors are numerous and their interrelationship not well understood. The aim of this study was to establish a multivariate prognostic model for acute and late dysphagia after RT, based on information from a prospective trial. Material and methods. The DAHANCA 6 & 7 randomized study included 1476 patients with head and neck cancer eligible for primary RT alone. Patients were randomized between 5 and 6 weekly fractions of conventional RT, and received 62-70 Gy in 31-35 fractions. Patients were scored for dysphagia weekly during treatment and at regular intervals until five years after treatment. Dysphagia scores were available from 1461 patients. Results. Acute dysphagia according to DAHANCA grades 1, 2, 3 and 4 occurred in 83%, 71%, 43% and 23%, respectively. Severe dysphagia occurred in 47% and 38% of patients receiving accelerated or conventional radiotherapy, respectively (p = 0.001). At one, two, three, four and five years the prevalence of chronic dysphagia above grade 0, was 46%, 32%, 29%, 24%, 23%, respectively with no difference between 5 and 6 fractions. In multivariate analysis, the following parameters were independent factors for severe acute dysphagia: T3-T4 tumors, N-positive disease, non-glottic cancer, age >median, baseline dysphagia >1 and accelerated radiotherapy. The following factors were prognostic factors for late dysphagia: non-glottic cancer, T3-T4, N-positive disease and baseline dysphagia >1. The data confirmed previously published predictive models, as it was possible to separate patients in groups with low, medium and high risk of dysphagia, respectively, based on pre-treatment risk scores. Conclusion. Prognostic models were established to characterize patients at risk of developing acute or late dysphagia in the DAHANCA 6 & 7 trial. The results may be useful to identify patients at risk of dysphagia and thus candidates for prophylactic measures against swallowing dysfunction.