Advertisement

NIH: Hyperthyroidism treatment may increase risk of cancer death

By Tauren Dyson

July 2 (UPI) -- A common treatment for hyperthyroidism is linked to an increase in the risk of cancer death, new findings show.

Every 100 milligray dose of radioactive iodine treatment for hyperthyroidism resulted in a 12 percent increase in breast cancer death risk, according to a study published Monday in JAMA. The same dosage led to 5 percent overall cancer death risk, as well, researchers report.

Advertisement

Hyperthyroidism, which can speed metabolism, cause unintentional weight loss and lead to heart problems, among other concerns, is found in about 1.2 percent of people in the United States. Women have a higher risk of developing the condition than men.

RAI, along with anti-thyroid drugs and surgery, is commonly used to treat hyperthyroidism.

"We identified a clear dose-response relationship between this widely used treatment and long-term risk of death from solid cancer, including breast cancer, in the largest cohort study to date of patients treated for hyperthyroidism," Cari Kitahara, a researcher at the National Cancer Institute's Division of Cancer Epidemiology and Genetics and study lead author, said in a news release.

"We estimated that for every 1,000 patients treated currently using a standard range of doses, about 20 to 30 additional solid cancer deaths would occur as a result of the radiation exposure," Kitahara said.

Advertisement

The researchers conducted a follow-up study based on findings from the Cooperative Thyrotoxicosis Therapy Follow-up Study. That research included more than 36,000 people with hyperthyroidism who received RAI treatment between 1946 and 1964.

For the new study, the researchers analyzed data on 19,000 people who didn't have cancer before enrolling in the Cooperative study. While most of the radiation went to the thyroid gland, some of it dispersed to other organs such as the stomach and breasts.

Between 19 to 32 solid-cancer deaths may be attributable to every 1,000 hyperthyroidism patients at age 40 who receive RAI treatment, researchers reported. This makes the potential for cancer significant, especially for breast cancer because of the large population of women treated for hyperthyroid, according to Kitahara.

"We found the increased risks of death from solid cancer overall and from breast cancer more specifically to be modest, but RAI is still a widely used treatment for hyperthyroidism," Kitahara said. "It's important for patients and their physicians to discuss the risks and benefits of each available treatment option. The results of our study may contribute to these discussions."

Latest Headlines