The evaluation of function and the ultrasonographic picture of thyroid in children treated for medulloblastoma

Abstract

Medulloblastoma (MB) is one of the most frequent and sensitive to radiation aggressive brain tumor in children. Abnormalities of the thyroid function are common complications of head and neck irradiation for childhood cancer. The aim of this study was to assess thyroid function in children treated for medulloblastoma according to the treatment protocol phase. Twenty-three children with MB were enrolled to this study. All patients underwent chemotherapy and radiotherapy to the whole craniospinal axis and boost with the conformal therapy restricted to the tumor bed to a total dose of 54 Gy. Thyroid function was evaluated based on thyroid-stimulating hormone (TSH), free thyroxine (fT4) levels controlled before MB treatment, directly after irradiation and at the end of the treatment protocol. Ultrasonography has been used to detect parenchymal abnormalities. All patients presented normal thyroid hormone range before chemotherapy. Hypothyroidism was found in 12 patients in the course of treatment, in 2 patients hormone deficits diagnosed directly after irradiation, in 10 patients such condition was observed at the end of the whole therapy. All of these patients needed thyroid hormone substitution. None of them presented clinical symptoms of hypothyroidism. Ultrasound-detected abnormalities have been found in 20 patients. It is crucial to monitor the functions of the thyroid gland in children treated for medulloblastoma because of the high risk of hypothyroidism resulting from the treatment. The change in the echogenicity of the thyroid gland may be an early marker for a dysfunction of this organ in children treated for medulloblastoma.