Pediatric patients with Down syndrome may undergo almost 10 times as many medical imaging examinations as other pediatric patients, potentially exposing them to more ionizing radiation, according to a recent study published by Marlow et al in PLOS ONE.
Ionizing radiation is present in many types of medical scans, such as chest x-rays and nuclear medicine. Although magnetic resonance imaging (MRI) scans, ultrasounds, and other commonly used scans don’t use radiation, individuals may also be introduced to small amounts of background radiation through exposure to the sun and atmosphere. Repeated exposure to radiation from any source can increase individuals’ risk of developing cancer. The cancer risk from radiation exposure in medical imaging is extremely small.
Investigators expressed cause for concern, however, in pediatric patients with Down syndrome, who often undergo extensive medical testing—including imaging that may involve ionizing radiation—for other conditions such as congenital heart disease and musculoskeletal conditions. Genetic disorders such as Down syndrome have an established increased risk of certain cancer types, making exposure to radiation early in life potentially hazardous. For instance, previous studies have indicated that patients with Down syndrome may be more susceptible to developing leukemia.
“For children with Down syndrome, specifically, we’re seeing an increase in CT imaging and angiography, both of which have a relatively high dose of radiation—many times more than standard radiographs,” explained lead study author Emily C. Marlow, PhD, MS, a postdoctoral fellow at the American Cancer Society. “We are concerned that [pediatric patients] with Down syndrome might be more sensitive to developing leukemia from radiation exposure,” she stressed.
Until recently, little research had been done to measure typical imaging radiation exposure rates for pediatric patients with Down syndrome.
Study Methods and Results
In this retrospective cohort study, investigators analyzed medical data from 4.3 million patients—3.1 million of whom were pediatric patients with Down syndrome—from six U.S. health-care systems between 1996 and 2016 to better understand the disparities in radiation exposure between pediatric patients with and without Down syndrome. The investigators then examined the radiation dose absorbed into the patients’ red bone marrow, which they estimated from patient data on medical scans, as the primary risk of radiation exposure as a result of its association with leukemia.
They found that pediatric patients with Down syndrome were exposed to ionizing radiation at significantly higher rates than other pediatric patients. On average, they received imaging at 9.5 times the rate of other pediatric patients before reaching 1 year of age and at 2.3 times the rate of other pediatric patients aged 1 to 18 years.
Although the risk of developing cancer from medical imaging may be small, the investigators recommended caution. For example, using a CT scan for a noncommunicative pediatric patient may be far easier than expecting them to lay still for an MRI.
“[Physicians] and parents just need to take into account how frequently the [pediatric patient] is being exposed [to ionizing radiation],” Dr. Marlow emphasized.
“The message we want to convey is that medical imaging should be used judiciously,” underscored co–senior study author Rebecca Smith-Bindman, MD, Professor of Epidemiology and Biostatistics and Director of the Radiology Outcomes Research Laboratory at the University of California, San Francisco. “Physicians and parents should work together to ensure that imaging is used only when there is clear need for additional information that imaging can provide, and that the potential benefit justifies the additional risk,” she concluded.
The investigators hope their new findings may help minimize the harms of medical imaging for pediatric patients with Down syndrome.
Disclosure: For full disclosures of the study authors, visit journals.plos.org.The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.