Biological dose-escalated definitive radiation therapy in head and neck cancer.

Objective: To compare treatment outcome of patients with head and neck (HN) tumours treated with definitive radiation therapy that, mainly owing to differences in the fractionation scheme used with simultaneous integrated boost techniques, resulted in a different biological dose.

Methods: 181 patients with HN cancer, prescribed to about 70.2 Gy in the primary tumour, were included in this study. Population cohort was divided into Group <70 and Group ≥70 when the mean dose converted to a 2 Gy fractionation in the primary tumour was less or higher than 70.2 Gy, respectively. The probability of local control (LC), locoregional control (LRC), disease-free survival (DFS) and overall survival (OS) was determined for both groups. The incidence of acute and late complications was compared between the two groups.

Results: At 24 months for Groups <70 and ≥70, LC was 83.2% and 87.5%, LRC was 79.5% and 81.6%, DFS was 56.3% and 66.8% and OS was 63.9% and 71.5% p = ns, respectively. The incidence of acute dysphagia, odynophagia and pain, and late mucositis was significantly higher in Group ≥70 than in Group <70. The rate of xerostomia, dysphonia, radiodermatitis, alopecia, dental complications, hypoacusia and weight loss was comparable between the two groups.

Conclusion: The biological dose escalation was safe, but an increase in the incidence of the acute side effects: dysphagia, odynophagia and pain and late mucositis, was obtained. Advances in knowledge: Despite the significant biological dose escalation, within the range of doses delivered to this cohort, no clear dose-response effect was observed.