Low doses of radioactive iodine for Hyperthyroidism has minimal cancer risk: JAMA

The primary outcomes were Cancer incidence and mortality for exposure vs non-exposure to RAI therapy and by the level of RAI administered activity.

The results of the study are as follows:

· Based on data from 12 studies including 479 452 participants, the overall pooled cancer incidence ratio was 1.02 and the pooled cancer mortality ratio was 0.98 for exposure vs non-exposure to RAI therapy.

· No statistically significant elevations in risk were observed for specific cancers except for thyroid cancer incidence and mortality.

· However, the inability to control for confounding by indication and other sources of bias were important limitations of studies comparing RAI exposure with non-exposure.

· In dose-response analysis, RAI was significantly associated with breast and solid cancer mortality, based on 2 studies.

Thus, the researchers concluded that that radiation-induced cancer risks following RAI therapy for hyperthyroidism are small and, in observational studies may only be detectable at higher levels of administered dose.

Reference:

Cancer Risk After Radioactive Iodine Treatment for Hyperthyroidism: A Systematic Review and Meta-analysis by Shim S et. al published in the JAMA Netw Open.

doi:10.1001/jamanetworkopen.2021.25072