THYROID: Edited by Angela M. LeungCancer incidence and mortality following treatment of hyperthyroidism with radioactive iodineEvron, Josh M.a; Esfandiari, Nazanene H.b; Papaleontiou, MariabAuthor Information aDivision of Endocrinology and Metabolism, Department of Internal Medicine, University of North Carolina, Chapel Hill, North Carolina bDivision of Metabolism, Endocrinology and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA Correspondence to Maria Papaleontiou, MD, Division of Metabolism, Endocrinology and Diabetes, Department of Internal Medicine, University of Michigan, North Campus Research Complex, 2800 Plymouth Road, Bldg 16, Rm 453S, Ann Arbor, MI 48109, USA. Tel: +1 734 764 9733; fax: +1 734 936 8944; e-mail: email@example.com. Current Opinion in Endocrinology & Diabetes and Obesity: October 2020 - Volume 27 - Issue 5 - p 323-328 doi: 10.1097/MED.0000000000000561 Buy Metrics Abstract Purpose of review Hyperthyroidism is a commonly encountered clinical issue. Radioactive iodine is one of the treatment modalities employed over the last 80 years. Prior studies are conflicting as to whether radioactive iodine is associated with an increased risk of subsequent malignancy and associated mortality. The present article reviews recent publications on this subject. Recent findings Two recent studies make meaningful contributions to the existing literature; however, data remain inconsistent. The first, conducted using the Clalit Health Services database, evaluated solid tumor incidence after radioactive iodine and found no association with increased risk of solid tumor malignancy. The second, which is an updated analysis of the Cooperative Thyrotoxicosis Therapy Follow-up Study, concluded that there is a dose-dependent increased risk of solid tumor mortality using a novel method of estimating organ-specific radiation exposure. Summary In patients with hyperthyroidism, radioactive iodine is a popular and effective treatment option. Prior studies reach conflicting conclusions on the potential relationship between radioactive iodine and both subsequent cancer incidence and mortality. We review recent publications that add to our understanding of this important clinical question. Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.