ULTRASONOGRAPHY FOR THYROID SCREENING AFTER HEAD AND NECK IRRADIATIONIN CHILDHOOD-CANCER SURVIVORS

We prospectively used ultrasonography to detect thyroid abnormalities in 96 long-term survivors of childhood cancer, who received head and n eck radiation therapy at a median age of 8.9 years. The median time in terval since irradiation was 10.8 years (range 5.6-22.8 years). Most s urvivors of leukemia received 24 Gy cranial irradiation for central ne rvous system prophylaxis; patients with solid tumors received between 20 and 66 Cy (median 37.5 Gy). The total evaluation included clinical history, physical examination, thyroid function tests, and thyroid ult rasonography; radionuclide scans were performed in patients whose abno rmalities persisted on subsequent ultrasound exams. Clinical history a nd physical examination revealed thyroid abnormalities in 14 patients (15%), but ultrasound detected abnormalities in 42 patients (44%). The se findings included inhomogeneity (n = 29), cysts (n = 15), and nodul es (n = 22) and occurred in nearly half of patients treated with 15 Cy or more directly to the thyroid gland. Radionuclide scans confirmed t he presence of thyroid nodules in 13 of 15 patients with ultrasonograp hic evidence of nodules. Six patients had thyroid neoplasia, including one case of papillary carcinoma. All patients with neoplasia had nodu les demonstrated on ultrasonography. Our experience suggests that in c hildhood cancer survivors, ultrasonography is a sensitive, affordable, and noninvasive means of detecting subtle parenchymal abnormalities. We recommend thyroid ultrasonography for childhood cancer survivors wh o recieved head and neck irradiation. A baseline study should be obtai ned within 1 year of completion of therapy. The frequency of subsequen t examinations should be based on the radiation dose and the patient's age at the time of irradiation. (C) 1997 Wiley-Liss, Inc.