Incidence of hypothyroidism after radiotherapy for nasopharyngeal carcinoma

Objectives: The thyroid gland is frequently affected by radiotherapy applied for the treatment of head and neck tumors. Hypothyroidism is observed as a late side effect of radiotherapy, especially seen in the patients who have surgery in the treatment procedure. Methods: We evaluated the radiation-induced hypothyroidism for a selected type of head and neck cancer-nasopharyngeal cancer (NPC)-which does not include surgery involving the thyroid gland in the treatment. Results: We observed 12 patients (14%) who developed hypothyroidism, two of which were subclinical hypothyroidism. The patients with hypothyroidism were statistically significantly younger than the euthyroid patients, but there were no statistically significant differences among the two groups in disease stages, radiotherapy neck doses, and gender. Conclusions: We recommend life-long TSH screening after RT to the neck owing to the incidence of RT-induced hypothyroidism and the importance of early thyroid hormone replacement therapy in patients becoming hypothyroid for maintaining optimal quality of life.