Continuing Occurrence of Thyroid Nodules After Head and Neck Irradiation

Abstract

Previously normal persons who had received head and neck irradiation (158 subjects) were re-examined. Twenty-four subjects had thyroid scintigrams that had changed in the follow-up interval of 24-60 (mean = 45.3) mo. Twelve subjects subsequently had thyroidectomy and 5 malignancies were found. In the other 12, the changes tended to be more subtle, but in 9 they very likely represented thyroid nodules. The prevalence of radiation-induced nodules is not decreasing. More changes (17 of 24) occurred in subjects who initially had elevated plasma thyroglobulin levels (P < 0.05). The difference was not significant when the analysis was limited to the almost certain development of a nodule. Longer follow-up will be needed to ascertain whether a high thyroglobulin level predicts a greater risk of developing thyroid nodules.