Evaluation of the effect of selenium on radiation-induced toxicities in head neck cancer patients

Abstract

e20698 Background: The substitution of selenium effects in activation of the selenium dependent enzyme glutathione peroxidase which is important for scavenging free radicals. Until today only limited data are available about the clinical impact of selenium regarding the toxicities due to free radical producing therapies, e.g. irradiation or chemotherapy. Methods: 39 patients (8 female, 31 male) with advanced head neck cancer were included to a randomized phase II study. All patients had shown a reduced concentration of selenium in the blood and serum (main inclusion criterium). The mean age was 63.52 ± 9.31 years. Tumour localizations: oral cancer 15 patients, oropharynx 19 patients, hypopharynx 5 patients, CUP 1 patient. Group A (n=22) received 500 μg sodium selenite at the days of radiotherapy and 300 μg sodium selenite at holidays or weekend. Group B (17) was irradiated without any selenium substitution. Both groups were well balanced according age, gender, localization and stage of the tumour. We evaluated the RTOG grade of radiation-associated toxicities once per week. Following statistical methods were used: Mantel-Haenssel-χ2-test, Fisher's exact Test. SPSS. Results: We observed the following serious toxicities (group A versus group B): dysphagia 22.7% vs. 35.3%, loss of taste 22.7% vs. 47.1%, dry mouth 22.7% vs. 23.5%, and stomatitis 36.4% vs. 23.5%. A statistical trend (Fisher's exact test) is only seen in the area of loss of taste (p=0.172). The analysis per week had only shown a significant reduction of dysphagia in the selenium group at the last week of irradiation (p=0.04). Conclusions: The small randomized trial has shown limited effects of selenium in the prevention of ageusia (loss of taste) and dysphagia due to radiotherapy because of head and neck cancer. A clinical relevant radioprotection was not observed. [Table: see text]