Radioactive Iodine Treatment Is Associated Modestly with Solid Organ Cancers

Although radioactive iodine (RAI) is used commonly for treating patients with Graves disease, clinicians and patients have expressed concern about radiation-induced cancers. In this prospective cohort study, researchers used a long-running U.S. and U.K. database to quantify cancer risk among 18,805 patients (mean age at database entry, 49) who were treated for hyperthyroidism between 1946 and 1964.

The investigators identified no statistically significant excess deaths from any specific solid organ cancer, although excess risk for developing breast cancer was of borderline significance (P=0.04). Risk for any solid cancer death increased with increasing amount of radiation exposure (i.e., a dose-response relation). In comparisons with expecte…