The prevalent use of CT scans may account for 1 in 20 cancers annually, according to new research.
The study, published Monday in JAMA Internal Medicine, suggests CT-related radiation is linked to even higher rates of cancer than previously thought. The 93 million CT scans performed in 2023 are projected to result in approximately 103,000 cancer diagnoses in the U.S. – approximately 5% of annual cancer diagnoses. That's three to four times higher than previous assessments and would put radiation from CT scans on par with alcohol and obesity as cancer risk factors.
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"Reducing the number of scans and reducing doses per scan would save lives," Dr. Rebecca Smith-Bindman, one of the study's authors, said in a news release. Smith-Bindman is a radiologist and professor at the University of California, San Francisco.
CT scans, which use computer tomography, have increased 30% from 68.7 million in 2007 to 93 million in 2023. They are more detailed than X-rays, but research has found radiation from CT scans is related to a higher risk of cancer. A 2009 study highlighted the need for greater standardization of the use of CT scans, finding that radiation doses from commonly used scans were higher than generally quoted.
The new study analyzed data from 61.5 million U.S. patients who had CT scans in 2023. Researchers found the number of scans increased by age, with people ages 60 to 69 accounting for the most. Children, who are more sensitive than adults to the negative impact of radiation, accounted for more than 4% of the scans.
Adults 50 to 59 were projected to have the greatest number of cancer diagnoses, with 10,400 cases for women and 9,300 for men. The most common adult cancers were lung, colon, leukemia, bladder and breast. Thyroid, lung and breast cancers most frequently were projected for children who underwent CT scans, according to the study.
"Few patients and their families are counseled about the risk associated with CT examinations," the study's co-author, Dr. Malini Mahendra, said in the release. "We hope our study's findings will help clinicians better quantify and communicate these cancer risks, allowing for more informed conversations when weighing the benefits and risks of CT exams."
CT scans of the abdomen and pelvis were projected to cause the greatest number of cancers. Full-body and spine CT scans also pose greater risk because they scan in multiple phases and involve higher doses of radiation, the researchers wrote.
"Justification of use and optimization of dose, including consideration of the need for multiphase examinations, are the tenets of CT imaging and must be applied uncompromisingly to mitigate potential harm," the researchers said.
