Reduced thyroid volume and hypothyroidism in survivors of childhood cancer treated with radiotherapy.

AIM: Children treated for cancer may have sequelae due to the treatment. The aim of this study was to assess the frequency of hypothyroidism and the thyroid volume of patients treated with radiotherapy for cancer during childhood.

PATIENTS: Fifty-nine patients treated with external beam radiation to different areas of the body during childhood.

METHODS: Cross-sectional study of patients assessed for late effects of external beam radiation treatment for childhood cancer. General and anthropometric characteristics, time from radiotherapy, family history of thyroid dysfunction, radiotherapy report, thyroid function tests, antithyroperoxidase antibodies and thyroid ultrasound were analyzed.

RESULTS: Hypothyroidism was found in 23 (39%) patients, 3.5 +/- 1.9 years after radiotherapy carried out at the mean age of 7.6 +/- 3.4 years. Site of irradiation had the greatest association with hypothyroidism. Anti-thyroperoxidase antibodies were normal in all patients. Thyroid volume was significantly lower in irradiated patients with hypothyroidism than in those with normal thyroid function (p <0.001).

CONCLUSIONS: Hypothyroidism is very common in survivors of childhood cancer treated with external beam radiation. Primary thyroid damage is suggested because of the smaller thyroid volume.