Thyroid function in survivors of cancer.

Thyroid function was assessed in three selected groups of children who had survived cancer. Children in group 1 had received radiotherapy to the thyroid area, group 2 had radiotherapy to the thyroid area and adjuvant chemotherapy, and group 3 had chemotherapy with or without radiotherapy away from the thyroid area. There were 75 survivors and 63 (40 boys, 23 girls) were available for study. Eighteen (29%) were found to have thyroid dysfunction, and these included all those who had had lymphangiograms or received a radiation dose greater than 40 Gy to the thyroid area. Only nine of the 18 children were already known to have thyroid dysfunction, and only 15 of 44 children who had had irradiation to the thyroid area had had their thyroid function examined. This study shows that children who have received radiotherapy to the thyroid area should have their thyroid function assessed regularly. Chemotherapy does not appear to be a risk factor but longer follow up of these children is necessary.