Thyroid disorders after radiation therapy in childhood

Abstract

Aim The aim of our study was to analyze thyroid status in adults after treatment for malignancies in childhood and its relationship with dose and type of radiotherapy. Material and methods Thyroid function (TSH, free T4, anti-TPO), thyroid ultrasound and FNA (in case of thyroid nodules more than 1 cm) were evaluated in 106 adults with a history of radiotherapy for brain tumors (BT), acute lymphoblastic leukemia (ALL) and Hodgkin's lymphoma (HL) in childhood and compared with that in healthy controls (n = 33). Group 1 (cranial irradiation 18 Gy): 11 men and 17 women (median age 21.7 ± 4.2 yrs (range 15–30)), 14.6 ± 4 years after treatment for ALL. Group 2 (craniospinal irradiation 35 Gy + boost to the tumor 55 Gy): 28 men and 20 women (median age 19.48 ± 2.76 yrs (range 15 – 26), 7.84 ± 4.68 years after treatment for brain tumors (BT). Group 3 (local irradiation of cervix and mediastinum mean dose 30.9 ± 9.17 Gy): 13 men and 16 women (median age 28.2 ± 6.31 yrs (range 17 – 44), 11.37 ± 7.25 years after treatment for HL. Results Maximal incidence of hypothyroidism was in the group 2 – 58.3% (35.4% – primary, 4.2% – central, 18.8% – mixed). Prevalence of hypothyroidism in groups 1 (9.09%) and 3 (17.24%) doesn't significantly differ from controls. Thyroid volume was lower (mean 4.58±2.39 ml) in group 2 (p0.001) in compare with other groups and control. TSH was higher (mean 3.72±2.51 MEd/l) in the same group in compare with group 1 and control (p=0.001). Incidence of thyroid nodules (10.34% – group 1; 8.3% – group 2; 20.7% – group 3) doesn't significantly differ between groups and controls (p=0.277). Conclusions These data indicate that treatment of cancer in childhood is associated with development of thyroid abnormality later during the life, and there is a possible link between craniospinal irradiation and incidence of hypo-thyroidism.

Keywords

• hypothyroidism
• radiotherapy
• radioinduced cancer
• thyroid