Abstract
Objective: To evaluate the acute effects of radiotherapy on the volume and function of the thyroid gland.
Material and Methods: Thirty-one patients with head and neck cancer were included in the study. Patients with thyroid cancer or thyroidectomy were excluded. There was no patient for whom radiotherapy was the only tretment modality. Thyroid function tests, thyroglobulin and thyroid volume imaging were evaluated before and immediately after radiotherapy,
Results: After radiotherapy 13 patients had dysfunction. Among 13, 8 had subclinical hyperthyroidism, 1 had clinical hyperthyroidism, 1 had subclinical hypothyroidism and 3 developed clinical hypothyroidism. After chemoradiotherapy all patients had significantly decreased FT3 (p<0.001). FT4 slightly increased in all of the patients other than operated patients (p>0.05). After treatment, the TSH decreased in patients who were not operated but given chemotherapy whereas it was increased in patients who were operated but not given chemotherapy (p>0.05). The thyroid volume was unchanged in 2 patients, decreased in 17 patients and increased in 12 patients (p>0.05). There was no correlation between chemotherapy or surgery, and the volume of the thyroid gland. No thyroiditis was seen in the acute phase.
Conclusion: Hyperthyroidism appeared immediately after radiotherapy. The volume of the gland starts to be slightly affected in the acute phase. Due to possible clinical thyroid dysfunction, after completion of the radiotherapy patients should not be discharged without thyroid function tests.