LAUSR

Key Points Question Is radioactive iodine absorbed dose associated with overall and site-specific cancer mortality in patients with hyperthyroidism? Finding In this cohort study of 18 805 patients with hyperthyroidism treated with radioactive iodine, a statistically significant positive dose-response relationship for risk of death was observed for all solid cancers (6% increase in risk per 100-mGy dose to the stomach), breast cancer (12% increase in risk per 100-mGy dose to the breast), and all solid cancers excluding breast (5% increase in risk per 100-mGy dose to the stomach). Meaning This study’s findings suggest a modest positive association between greater organ-absorbed doses of radioactive iodine and risk of solid cancer death; additional studies are needed to fully weigh the risks and advantages of radioactive iodine and other treatment options for patients with hyperthyroidism.