Study Links Medical Scans to Increased Cancer Risk in Children

A recent study backed by government funding indicates that excessive radiation from certain medical scans could significantly elevate cancer risk in children.

Each year, roughly 61 million Americans, or around 18 percent of the population, undergo various imaging tests like CT scans, which utilize radiation to generate detailed images of the body.

While these tests play a crucial role in identifying injuries and chronic illnesses, repeated exposure to radiation—a carcinogen—can accumulate in the body over time.

In light of these concerns, researchers in California analyzed data from nearly four million children in the U.S. and Canada to assess how radiation exposure impacts cancer risk.

The findings suggest that about one in ten cases of blood cancers in children, totaling around 3,000, could be linked to radiation exposure from scans like CTs.

Interestingly, just one or two head CT scans were associated with a nearly doubled risk of developing cancer. Moreover, children who had multiple scans were over three times more likely to receive a cancer diagnosis compared to those who didn’t undergo these tests.

The researchers posited that about ten percent of blood cancers in children and teenagers could be completely preventable by minimizing unnecessary imaging and reducing radiation exposure.

They recommended utilizing alternative methods, such as ultrasound or MRI, which do not involve radiation.

Dr. Rebecca Smith-Bindman, the lead author and a radiologist from the University of California, San Francisco, remarked that children are particularly susceptible to radiation-induced cancers due to their greater radiosensitivity and longer life expectancy.

She emphasized that, although medical imaging is vital, it is essential to carefully assess and minimize radiation exposure during pediatric imaging to ensure long-term health.

The goal, she noted, should be to conduct imaging only when it is absolutely necessary for a child’s care and to employ the lowest radiation doses possible, particularly with CT scans.

Each year, about 15,000 American children are diagnosed with cancer, with leukemia being the most prevalent type, representing roughly 30 percent of annual cases.

Sadly, around 1,600 children in the U.S. die from cancer yearly.

Recent studies also indicate that childhood cancers have risen by approximately 35 percent over the last fifty years, a trend experts attribute not just to advancements in diagnostic tools, but also to increased environmental exposures, including radiation and pollution.

The study, published in the New England Journal of Medicine, tracked a group of 3.7 million children born between 1996 and 2016 across six U.S. healthcare systems and Ontario.

Participants were observed from birth until they were either diagnosed with cancer or a benign tumor, lost healthcare coverage, turned 21, or until the study ended on December 31, 2017.

The above shows the relative risks for blood cancers in children according to cumulative radiation exposure

Half of the participants were male, with the largest group (43 percent) being born between 1996 and 2004. During the study, 4,916 children (or 0.1 percent) died.

Out of the total, 2,961 were diagnosed with blood cancer, with lymphoma representing 80 percent of cases, while leukemia and bone marrow cancer accounted for 15.5 percent. The remainder comprised rarer types of cancers affecting white blood and immune cells.

Significantly, about 58 percent of the cancer cases were in males, and over half occurred in children under five.

The study indicated that for children who underwent head CT scans, approximately 25 percent of their cancers could be attributed to radiation exposure.

Moreover, having one or two CT scans was linked to a 1.8-fold increased risk of blood cancer, which rose to 3.5 times with repeated scans.

The research team estimated that medical imaging contributed to about ten percent of blood cancers in their cohort.

This risk is partly attributed to the inconsistent levels of radiation exposure, which can vary significantly between different machines.

While CT scans can be essential for diagnosing conditions early, they are sometimes overused. This is likely due to financial motivations for hospitals and the fear among doctors of overlooking critical diagnoses.

The above shows the risk of blood cancers after exposure to radiation

Radiation is a recognized carcinogen capable of damaging DNA within cells, leading to uncontrolled cellular growth that can result in cancer. Additionally, it produces free radicals that harm DNA and other cellular components, causing inflammation.

The radiation from CT scans is absorbed readily by bones, increasing the likelihood of blood and bone marrow cancers.

The researchers are urging healthcare providers to limit the use of radiation-based scans when possible, suggesting alternatives like MRI or ultrasound, which are safer.

Dr. Diana Miglioretti, co-author and professor at UC Davis Health, pointed out that the study provides solid evidence of a clear connection between radiation exposure from medical imaging and the risk of blood cancers in children and adolescents.

She reiterated the importance of balancing the immediate benefits of imaging against long-term health risks and optimizing imaging practices to minimize radiation exposure.

This research received funding from the National Cancer Institute and various grants from the Ontario Ministry of Health and Long-Term Care.

Previous findings by Dr. Smith-Bindman suggested that over 100,000 new cancers could arise from CT scans performed in 2023 alone. Her earlier research estimated that CT-related cancers might eventually comprise five percent of annual new cancer diagnoses.