MON-579 Toxic Multinodular Goiter And Thyroid Cancer Risk

Toxic multinodular goiter (TMNG) occurs when there is overproduction of thyroid hormones by one or more autonomously functioning nodule. The hyperthyroidism of TMNG does not remit spontaneously, thus patients with TMNG are usually treated with radioiodine (RAI) or surgery. Many studies have reported the prevalence of incidental cancers found in thyroidectomy specimens of MNG to range from 4-10 %, and the majority of these incidental cancers are micro-papillary. But whether these cancers progress to clinical disease is not well established. The objective of this study was to assess the clinical outcomes of patients with TMNG following radio-iodine ablation therapy. We conducted a retrospective chart review of subjects who received radio-iodine ablation therapy in a single academic medical center from January 2010 to March 2018. Medical records of all subjects were reviewed to determine those with TMNG, and the outcomes of their treatment. Results: A total of 228 subjects who received radio-iodine therapy were reviewed. 33 were identified with a diagnosis of TMNG based on thyroid US, TSH and free T4 levels, and the findings of a thyroid -uptake scan. 12 of 33 subjects had follow-up US and sufficient clinical data. Their median age was 61 yrs (range 38-87 yrs), 11 females (91.7%) and 1 male (8.3%), with follow-up of 9-103 months. Subsequent US revealed a decrease in nodule size in 8 (66.7%), and no change in 2 (16.7%), while in 2 patients (16.7%) the nodules were thought to have increased in size, and will have an FNA. 3 patients with suspicious nodules on US underwent FNA; all were negative for malignancy. One patient underwent total thyroidectomy concurrent with surgery for a parathyroid adenoma; thyroid pathology was negative. No patients have been diagnosed with thyroid cancer. From these preliminary results, we believe that the risk of developing thyroid cancer in patient with TMNG who undergo radio-iodine ablation therapy is low. Nodules in patients with TMNG with suspicious US characteristics should be managed like thyroid nodules in euthyroid patients according to guidelines. Surgery as first line treatment in TMNG patients may not be justified