Thyroid toxicity of treatment for Hodgkin's disease

Thyroid disease, especially hypothyroidism, is one of the more frequently e ncountered late endocrine sequelae of treatment for Hodgkin's disease. We a nalyzed the thyroid function of 177 patients (92 male and 85 female) who ha d been treated for Hodgkin's disease between 1970 and 1995; their median ag e was 38 years (range 18-74) and their median time after therapy was 6 year s (range 1-20), Thirty-five (20%) patients were treated with chemotherapy a lone (mainly COPP/ABVD), 44 (25%) with radiotherapy (RTX) alone. and 98 (55 %) received combined modality treatment according to the protocols of the G erman Hodgkin's Disease Study Group. All patients had been without evidence of disease for at least 1 year. They were evaluated between 1994 and 1997 for thyroid disease by clinical examination, thyroid function tests, and ul trasound imaging if indicated. Overall, 48 patients (27%) were found to hav e subclinical (36 patients, 20%) or overt (12 patients, 7%) hypothyroidism. No patient in the group treated with chemotherapy alone developed hypothyr oidism. in contrast to 15 of 44 (34%) patients treated with radiotherapy al one and 33 of 98 (34%) patients treated with the combined modality approach who did. All patients with hypothyroidism had received some form of suprad iaphragmatic radiation except one patient who underwent infradiaphragmatic RTX but with preceding hemithyroidectomy for staging purposes. After an ave rage follow-up of 6 years, 27% of patients treated fur Hodgkin's disease wi th either radiotherapy alone or a combination of radiotherapy and chemother apy developed hypothyroidism. Supradiaphragmatic radiation, but not the use of chemotherapy alone, is associated with an increased risk for hypothyroi dism. Evaluation of thyroid function after therapy is important, and approp riate substitution medication should be initiated.