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.