Objective: Benign thyroid nodules are increased by radiation exposure and recurrences are common. The goal of this study was to determine the factors related to recurrence of nodular disease and the efficacy of thyroid hormone therapy in reducing them.
Design, setting, and subjects: The study population was drawn from a cohort of 4296 people treated before the age of 16 with conventional external radiation for benign conditions of the head and neck between 1939 and the early 1960s. The study group consisted of 632 subjects who had benign nodules removed surgically. At the discretion of their physicians, 426 subjects were treated with thyroid hormone after surgery, 198 were not, and in 8 subjects, thyroid hormone treatment status was unknown.
Main outcomes: There were 129 (20.4%) subjects who developed new nodules during follow-up. Women had a greater risk of recurrent nodules than men (27.5% vs. 13.5%) and the rate of recurrence correlated inversely with the extent of surgery. The group who took thyroid hormone had a lower recurrence rate than the untreated group (14.2% vs. 34.2%). The risk of recurrence was reduced to 0.69 (0.47-1.01) in thyroid hormone-treated subjects, regardless of extent of surgery, and to 0.66 (0.46-0.97) when only the subjects with less than 75% of their thyroid removed were considered.
Conclusion: Thyroid hormone therapy reduced recurrences in this irradiated cohort. It should be recommended to all patients with irradiated thyroids and previous thyroid surgery.