Head and neck irradiation in childhood: increased risk of developing thyroid disease

A Comparison of Total Thyroidectomy and Lobectomy in the Treatment of Dominant Thyroid Nodules

Patients with a clinically concerning dominant thyroid nodule have been managed by lobectomy or total thyroidectomy at our institution. We determined the complications associated with both approaches and the ability of thyroid lobectomy to avoid the need for thyroid hormone replacement therapy. Records of all patients with a dominant thyroid nodule managed with surgery from August 1993 through December 2000 were reviewed for demographics, history of head and neck radiation, indication for surgery, preoperative fine-needle aspirate results, final pathologic evaluation, perioperative complications, determinations of need for subsequent thyroid surgery after lobectomy, and need for thyroid hormone replacement therapy after surgery. Patients with a preoperative diagnosis of malignancy or bilateral or diffuse disease were excluded because these conditions would uniformly be managed by bilateral thyroidectomy. The complications for the lobectomy group (n = 131) compared with the total thyroidectomy group (n = 84) were: recurrent laryngeal nerve paresis (4.6% vs 2.4%), recurrent laryngeal nerve injury (0.8% vs 0), and transient hypoparathyroidism (1.5% vs 9.5%; P = 0.007). No permanent hypoparathyroidism was identified in either group. Postoperative thyroid hormone replacement was required in 64 of 131 lobectomy patients (48.8%). Complications associated with either surgery were low. Total thyroidectomy was not associated with clinically significant additive morbidity. Patients treated by lobectomy should be aware of a nearly 50 per cent chance of requiring thyroid hormone replacement. Total thyroidectomy avoids future thyroid surgery; lobectomy patients remain at risk. When complications can be minimized total thyroidectomy should be considered an option in the management for patients with dominant thyroid nodules that require surgery.

Ultrasonography for thyroid screening after head and neck irradiation in childhood cancer survivors

We prospectively used ultrasonography to detect thyroid abnormalities in 96 long-term survivors of childhood cancer, who received head and neck radiation therapy at a median age of 8.9 years. The median time interval since irradiation was 10.8 years (range 5.6-22.8 years). Most survivors of leukemia received 24 Gy cranial irradiation for central nervous system prophylaxis; patients with solid tumors received between 20 and 66 Gy (median 37.5 Gy). The total evaluation included clinical history, physical examination, thyroid function tests, and thyroid ultrasonography; radionuclide scans were performed in patients whose abnormalities persisted on subsequent ultrasound exams. Clinical history and physical examination revealed thyroid abnormalities in 14 patients (15%), but ultrasound detected abnormalities in 42 patients (44%). These findings included inhomogeneity (n = 29), cysts (n = 15), and nodules (n = 22) and occurred in nearly half of patients treated with 15 Gy or more directly to the thyroid gland. Radionuclide scans confirmed the presence of thyroid nodules in 13 of 15 patients with ultrasonographic evidence of nodules. Six patients had thyroid neoplasia, including one case of papillary carcinoma. All patients with neoplasia had nodules demonstrated on ultrasonography. Our experience suggests that in childhood cancer survivors, ultrasonography is a sensitive, affordable, and noninvasive means of detecting subtle parenchymal abnormalities. We recommend thyroid ultrasonography for childhood cancer survivors who received head and neck irradiation. A baseline study should be obtained within 1 year of completion of therapy. The frequency of subsequent examinations should be based on the radiation dose and the patient's age at the time of irradiation.

Sonographic abnormalities of the thyroid gland following radiotherapy in survivors of childhood Hodgkin's disease

The aims of this study were as follows. (1) To demonstrate the spectrum, frequency and changes on follow-up of sonographic abnormalities in the thyroid gland of survivors of Hodgkin's disease who had received radiotherapy to the neck in childhood. (2) To compare the sonographic findings with clinical examination and radionuclide imaging. (3) To investigate the association between the presence or absence of focal sonographic abnormalities with age at radiotherapy, the interval from radiotherapy, the presence of a raised thyroid stimulating hormone (TSH) and the length of time the TSH had been raised. 46 patients were scanned prospectively and rescanned at 6-18 months. The mean age at first sonography was 22.7 years, the median age at radiotherapy was 12.5 years, and the median interval post-radiation was 10.3 years. Sonographic abnormalities were seen in all 46 patients. 45 had diffuse atrophy and 30 had focal sonographic abnormalities. 18 patients developed new focal sonographic abnormalities on follow-up. Focal sonographic abnormalities were more commonly associated with longer duration of a raised TSH. Two patients had thyroid carcinoma. Sonographic abnormalities of the thyroid are common in patients following neck radiotherapy in childhood. Focal abnormalities are usually associated with a longer duration of raised TSH.