Thyroid diseases after treatment of Hodgkin's disease.

BACKGROUND AND METHODS

Thyroid disease, especially hypothyroidism, is common in patients with Hodgkin's disease who have been treated with irradiation. We reviewed the records of 1787 patients (740 women and 1047 men) with Hodgkin's disease who were treated with radiation therapy alone (810 patients), radiation and chemotherapy (920 patients), or chemotherapy alone (57 patients) at Stanford University between 1961 and 1989. Among these patients, 1533 were alive at the last follow-up, and 254 had died of causes other than Hodgkin's disease. (Four other patients were excluded from the analysis because they had undergone thyroidectomy before treatment for Hodgkin's disease. The thyroid was irradiated in 1677 patients. Follow-up averaged 9.9 years.

RESULTS

A total of 573 patients had clinical or biochemical evidence of thyroid disease. Among the 1677 patients whose thyroid was irradiated, the actuarial risk of thyroid disease 20 years after treatment was 52 percent, and it was 67 percent at 26 years. Hypothyroidism was found in 513 patients. A total of 486 patients received thyroxine therapy for elevated serum thyrotropin concentrations and either low free thyroxine (208 patients) or normal free thyroxine values (278 patients); 27 had transient elevations of the serum thyrotropin level that were not treated. Graves' hyperthyroidism developed in 30 patients (2 of whom had not undergone thyroid irradiation), and ophthalmopathy developed in 17 of these patients. Ophthalmopathy developed in four other patients with Graves' disease during a period of hypothyroidism (n = 3) or euthyroidism (n = 1). The risk of Graves' disease was 7.2 to 20.4 times that for normal subjects. Silent thyroiditis with thyrotoxicosis developed in six patients. Forty-four patients were found to have single or multiple thyroid nodules, 26 of whom underwent thyroidectomy. Six of the 44 had papillary or follicular cancers. Among the patients who did not undergo operation, 12 had small functioning nodules, 4 had cysts, and 2 had multinodular goiters. The actuarial risk of thyroid cancer was 1.7 percent. The risk of thyroid cancer was 15.6 times the expected risk.

CONCLUSIONS

High risks of thyroid disease persist more than 25 years after patients have received radiation therapy for Hodgkin's disease, reinforcing the need for continued clinical and biochemical evaluation. Prolonged follow-up confirms an elevated risk of thyroid cancer and Graves' disease as well as hypothyroidism in these patients.