Does vitamin E protect salivary glands from I-131 radiation damage in patients with thyroid cancer?

OBJECTIVES

Salivary gland impairment after high-dose radioiodine (¹³¹I) treatment is well recognized. The aim of this study was to determine the protective effect of vitamin E on radiation-induced salivary gland dysfunction in patients undergoing ¹³¹I treatment for differentiated thyroid cancer.

METHODS

Thirty-six patients with differentiated thyroid carcinoma were enrolled in this study. They were randomly divided into two groups before postsurgical ablation therapy with 3700-5550 MBq ¹³¹I: the control group, comprising 17 patients, and the vitamin E group, comprising 19 patients. All 19 patients in the experimental group received vitamin E at a dose of 800 IU/day for a duration of 1 week before to 4 weeks after I therapy and the 17 patients in the control group received a placebo for the same duration. Salivary gland function was assessed using salivary gland scintigraphy with intravenous injection of 370 MBq Tc-pertechnetate in two phases, one immediately before and the other 6 months after ¹³¹I ablative therapy. First-minute uptake ratio, maximum uptake ratio, maximum secretion percentage, and excretion fraction (EF) of each salivary gland were measured and compared between the study phases for the two groups.

RESULTS

There was no significant difference between preablative and postablative salivary scintigraphic indices in the experimental vitamin E group, whereas maximum secretion percentage and EF of the right submandibular gland and EF of the left parotid gland were significantly decreased in the control group. There was also a higher significant decrease in the EF of the left parotid gland in the control group compared with the vitamin E group.

CONCLUSION

Vitamin E consumption may be associated with a significant protective effect against radiation-induced dysfunction in salivary glands following single-dose ¹³¹I therapy in patients with differentiated thyroid cancer.