Research conducted by endocrinologists at the University of Rochester Medical Center has revealed that being exposed to radiation in childhood may increase a person's risk of developing thyroid cancer later in life.
Published in the journal Radiation Research, the study found that children who received low-dose chest radiation treatment for an enlarged thymus grew up to be more than five times more likely to have thyroid cancer.
The study's authors wrote that the enlargement of the thymus, a gland between the lungs that produces immune cells, is rarely considered a medical problem today. However, it was treated as one between the 1950s and the 1980s, when the study's participants received radiotherapy for it.
Even after adjusting their data for age, gender and history of goiter, the team found that childhood radiation therapy increases the risk of thyroid cancer for nearly 60 years after it is administered.
They added that the risk drops off after an individual has lived six decades beyond the original treatment. Lead author Jacob Adams suggested that the use of radiation-based medical scans may be at least partially to blame for the increasing rate of thyroid cancer in the U.S.
He wrote that computer tomography (CT) scans and magnetic resonance images (MRIs) are often used to diagnose medical conditions in young children. According to the study, more than one million CT scans are taken of children aged 5 or younger every year in the U.S.
"Ionizing radiation is a known carcinogen," Adams said. He and his research team suggested that more attention be paid to the types and amounts of radiation being used to diagnose illnesses in children, even though current MRI and CT technologies use less radiation than earlier versions.
Researchers concluded that diagnostic irradiation of children under 5 should be avoided when possible. Over a lifetime, approximately one in 111 Americans develop some form of thyroid cancer, according to the National Cancer Institute.