Limited effects of selenium substitution in the prevention of radiation-associated toxicities. results of a randomized study in head and neck cancer patients

Abstract

Objective: The substitution of selenium activates the selenium-dependent enzyme glutathione peroxidase, which is important for scavenging free radicals. To date, 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, and therefore the objective of this study was to investigate the clinical impact of selenium in such therapies.

Patients and methods: 39 patients (8 female, 31 male) with advanced head and neck cancer were included in a randomised phase II study. The mean age was 63.52+/-9.31 years. Tumour localizations: oral cavity 15 patients, oropharynx 19 patients, hypopharynx 5 patients, carcinoma of unknown primary 1 patient. Group A (n=22) received 500 microg sodium selenite on the days of radiotherapy and 300 microg sodium selenite on days without radiotherapy. Group B (17) was irradiated without any selenium substitution. Both groups were well balanced according to age, gender, localization and stage of the tumour. The RTOG grade of radiation-associated toxicities was evaluated once per week.

Results: The following serious toxicities were observed (group A vs. 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) was only seen for the loss of taste (p=0.172). The weekly patient analysis (Student's t-test) showed a significant reduction of dysphagia in the selenium group (Group 1) at the last week of irradiation.

Conclusion: This small randomised trial showed limited effects of selenium in the prevention of ageusia (loss of taste) and dysphagia due to radiotherapy of head and neck cancer.