In a study published September 17 in the New England Journal of Medicine, a team led by Rebecca Smith-Bindman, MD, of the University of California, San Francisco reported results suggesting that exposure to radiation from medical imaging is linked to increased risk of blood cancers among children.
The group’s analysis included data from more than 3.7 million children born in the U.S. or Ontario, Canada (taken from the Risk of Pediatric and Adolescent Cancer Associated with Medical Imaging [RIC] retrospective cohort study), and found that medical imaging was associated with 10.1% of hematologic cancers in this population.
Smith-Bindman has been investigating the effects of CT radiation dose on patients for decades. This latest study follows on another that her group published in April in JAMA Internal Medicine that suggested that cancers associated with radiation from CT scans could eventually account for 5% of all new cases annually. That research elicited responses from the American Association of Physicists in Medicine (AAPM) and the American College of Radiology (ACR). As well, she is a founding member of Alara Imaging, which offers free HIPAA- and SOC-II-certified software to help physicians and health systems comply with U.S. Centers for Medicare & Medicaid Services’ (CMS) CT radiation dose quality measures.
In an interview with AuntMinnie.com, Smith-Bindman described the NEJM study’s methodology and underscored the importance of medical imaging to patient care, while also urging professional associations and radiologists to carefully consider the appropriate use of CT, especially for children.
She addressed the need to assess the harm/benefit ratio when it comes to pediatric CT imaging, noting that “medical imaging is an incredibly important and it’s essential for diagnosing and managing disease,” but that it must be “performed only when it provides essential information for a child’s care.”
The use of CT in children has been on the rise, even though there aren’t necessarily new clinical scenarios that would prompt this, according to Smith-Bindman.
“This paper [has] raised the need to justify imaging and to use the lowest dose as possible,” she said.
If the reason for the scan is “just to see” — and the test doesn’t necessarily change patient management — “that’s an exam where there is no benefit and the small risk [of cancer] becomes all that there is,” Smith-Bindman said. She noted that in many instances, appendicitis for example, there are imaging exams such as ultrasound that don’t impart radiation.
“CT [is often used as a] first line for appendicitis when ultrasound is a really good test,” she said.
Finally, Smith-Bindman discussed the study’s research methodology, explaining that, among other protocols, she and her team adjusted for a bias called reverse causation (for example, a child might have a symptom that could be related to cancer and undergoes CT; the exam doesn’t show anything but the child is diagnosed with leukemia five months later, which suggests the disease was present beforehand and wasn’t caused by radiation exposure on CT), eliminating exams that occurred within six months of a cancer diagnosis.
“We designed the study to address methodological shortcomings of prior work,” she said. “[Our] results are very strong, very consistent, and provide really robust evidence that radiation from imaging is associated with hematological cancer [in children], even at lower doses.”