[Thyroid function alteration in patients with radiation therapy of the neck].

INTRODUCTION

The aim of this study is to determine whether the incidence of hypothyroidism in patients with Head and Neck Cancer who have undergone neck radiotherapy justifies the inclusion of thyroid function monitoring in the pre-operative and follow-up evaluation protocols.

MATERIAL AND METHODS

A retrospective study was conducted with all the patients seen in the Oncology Section of the Otorhinolaryngology Department in the "Hospital de Clínicas", Montevideo, Uruguay, from January 1970 to May 2008. A total of 550 case records were analyzed. Of the 550 patients, 188 were excluded due to the fact they had not received radiotherapy as part of their treatment and 362 were included in the study. Of these, 55 patients had thyroid stimulating hormone (TSH) level determination after treatment with radiation therapy. Hypothyroidism was defined as a TSH value greater than or equal to 4.5 mIU/L, regardless of whether or not any symptoms were presented.

RESULTS

36.4% of the patients were diagnosed as having clinical or sub-clinical hypothyroidism. The type of treatment carried out, particularly whether or not surgical resection was performed, was found to be the most significant predictive factor for the development of hypothyroidism (P=0.054).

CONCLUSION

Monitoring of the thyroid function on a six-month or annual basis, at least during the first 5 post-treatment years, has to be included in the follow-up and control protocols of every patient undergoing neck RT, and patients with TSH values over 4.5 mIU/L should be referred to the endocrinologist for hormone replacement, whether they present symptoms or not.