Thyroid Dysfunction Following Therapeutic External Radiation to Head and Neck Cancer

Aim: The aim of the present study was to evaluate changes in thyroid function in patients with head andneck cancer treated with external beam radiotherapy (EBRT). Materials and
Methods: This prospective studywas conducted on ninety patients with non-thyroid head and neck cancer who were referred to the departmentof radiotherapy. Thyroid function tests were conducted before, midway during and after EBRT, with followup at monthly intervals up to 6 months after the completion of therapy.
Results: Serum T3 and T4 levels weredecreased at completion of EBRT and remained so after 6 months follow up. However, serum TSH levels didnot significantly vary.
Conclusion: EBRT to the neck region for treatment of head and neck cancer induceshypothyroidism and therefore utmost care must be taken to exclude the thyroid from radiation beams withoutsparing the tumor as far as possible. The clinical protocol in such cases should include monitoring of T3, T4 andTSH levels during and after the EBRT.