Authored By:
Inskip et alThis was a cohort study investigating the risk of developing hyperthyroidism following incidental radiation exposure to the thyroid and the pituitary gland during radiation therapy for childhood (<21 years) cancer. The study included 11,608 childhood cancer patients, of which 148 self-reported to have been diagnosed with hyperthyroidism by a doctor more than 5 years after their first radiotherapy treatment. The study did not show a statistically significant increase in the risk of developing hyperthyroidism from radiotherapy exposure to the pituitary gland. However, the study did show a statistically significant increase in the risk of hyperthyroidism associated with a dose to the thyroid above 25 Gray (Gy) (relative risk 3.1; 95% confidence interval (CI) of 1.3-7.2). The authors also reported a linear dose response between radiation received by the thyroid and excess relative risk of developing hyperthyroidism per Gy of 0.06 (95% CI of 0.03-0.14). The authors concluded the results supported radiation exposure as a risk factor for hyperthyroidism. Further, the authors concluded that the results were consistent with the linear no threshold model. However, the risk was concluded to be relatively small, except at therapeutic doses.
Published In:
International Journal of Radiation Oncology, 2019The study reported increased risk of developing hyperthyroidism per Gy of radiation exposure of 0.06. However, the results demonstrated that below 25 Gy the risk of developing hyperthyroidism was not significant. The United Nations Scientific Committee on the Effects of Atomic Radiation also reports an increased relative risk of hyperthyroidism following radiation treatment for childhood cancer. The Inskip et al study overall was large, however, the findings are limited by the small number of cases of hyperthyroidism.
The study by Inskip et al is one of many studies that have examined the data from the US/Canadian childhood cancer survivor study. These studies have examined the possible latent health effects in children after diagnoses and treatment of a range of cancers after 5 years.
