- Radioactive iodine (RAI) treatment is associated with excess risk for death from solid cancer in patients with hyperthyroidism.
Why this matters
- RAI is commonly used for hyperthyroidism treatment and is widely considered to be safe and effective.
- Organ-absorbed doses are positively associated with solid cancer mortality.
- Malignancy was the primary cause of death in 15.3% of patients.
- RAI was associated with all solid cancer mortality (relative risk [RR], 1.06; P=.002 for 100-mGy dose to the stomach).
- Breast cancer: RR, 1.12; P=.04 for 100-Gy dose to the breast.
- All other solid cancers combined: RR, 1.05; P=.01 for 100-Gy dose to the stomach.
- For patients receiving typical RAI doses (150-250 mGy) to the stomach, lifetime excess solid cancer deaths were estimated as 19-32 per 1000 patients treated at age 40 years and 18-31 per 1000 patients treated at age 50 years.
- 18,805 patients with hyperthyroidism treated with RAI with no history of cancer were included.
- This study is a 24-year extension of the multicenter Cooperative Thyrotoxicosis Therapy Follow-up Study.
- Funding: Intramural Research Program of the National Cancer Institute, NIH.
- Uncertainties in organ dose estimations.
- Limited statistical power for many cancers of interest.
- Results unadjusted for smoking, obesity, alcohol use, or reproductive factors.