Abstract
Importance: Approximately 93 million computed tomography (CT) examinations are performed on 62 million patients annually in the United States, and ionizing radiation from CT is a known carcinogen.
Objective: To project the number of future lifetime cancers in the US population associated with CT imaging in 2023.
Design, setting, and participants: This risk model used a multicenter sample of CT examinations prospectively assembled between January 2018 and December 2020 from the University of California San Francisco International CT Dose Registry. Data analysis was conducted from October 2023 to October 2024.
Main outcomes and measures: Distributions of CT examinations and associated organ-specific radiation doses were estimated by patient age, sex, and CT category and scaled to the US population based on the number of examinations in 2023, quantified by the IMV national survey. Lifetime radiation-induced cancer incidence and 90% uncertainty limits (UL) were estimated by age, sex, and CT category using National Cancer Institute software based on the National Research Council's Biological Effects of Ionizing Radiation VII models and projected to the US population using scaled examination counts.
Results: An estimated 61 510 000 patients underwent 93 000 000 CT examinations in 2023, including 2 570 000 (4.2%) children, 58 940 000 (95.8%) adults, 32 600 000 (53.0%) female patients, and 28 910 000 (47.0%) male patients. Approximately 103 000 (90% UL, 96 400-109 500) radiation-induced cancers were projected to result from these examinations. Estimated radiation-induced cancer risks were higher in children and adolescents, yet higher CT utilization in adults accounted for most (93 000; 90% UL, 86 900-99 600 [91%]) radiation-induced cancers. The most common cancers were lung cancer (22 400 cases; 90% UL, 20 200-25 000 cases), colon cancer (8700 cases; 90% UL, 7800-9700 cases), leukemia (7900 cases; 90% UL, 6700-9500 cases), and bladder cancer (7100 cases, 90% UL, 6000-8500 cases) overall, while in female patients, breast was second most common (5700 cases; 90% UL, 5000-6500 cases). The largest number of cancers was projected to result from abdomen and pelvis CT in adults, reflecting 37 500 of 103 000 cancers (37%) and 30 million of 93 million CT examinations (32%), followed by chest CT (21 500 cancers [21%]; 20 million examinations [21%]). Estimates remained large over a variety of sensitivity analyses, which resulted in a range of 80 000 to 127 000 projected cancers across analyses.
Conclusions and relevance: This study found that at current utilization and radiation dose levels, CT examinations in 2023 were projected to result in approximately 103 000 future cancers over the course of the lifetime of exposed patients. If current practices persist, CT-associated cancer could eventually account for 5% of all new cancer diagnoses annually.
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CT scans, or CAT scans, are widely used to get internal images of the body and diagnose dangerous medical conditions — but they could pose a hidden risk.
A new study from the University of California - San Francisco found that CT (computed tomography) scans could be responsible for 5% of all cancer diagnoses each year, according to a press release.
"While some uncertainty exists, it doesn’t significantly affect the core conclusion: A small but meaningful percentage of cancers are linked to CT scans, and this number can be reduced," first author Rebecca Smith-Bindman, MD, a UCSF radiologist and professor, told Fox News Digital.
The researchers’ estimates show that the ionizing radiation exposure from CT scans is comparable to other significant risk factors, such as alcohol consumption and excess body weight.
To predict how many future cancers could result from current CT scans, the researchers updated a previous analysis of 2023 data on scan volumes, scan types and radiation doses, according to Smith-Bindman.
"We used a well-validated model to estimate cancer risk and conducted sensitivity analyses to confirm the robustness of our findings," she said.
"This is a modeling study, meaning our conclusions depend on the accuracy of the data used."
Based on the review, the researchers estimate that approximately 103,000 future cancers will be caused by CT scans performed in 2023 in the U.S., with the highest number of cases affecting adults aged 50 to 69.
Individual cancer risk is highest for babies and children, with babies under 1 year old 10 times more likely to develop the disease compared to others in the study.
Adults, however, account for the majority of scans, which drives the overall cancer burden, Smith-Bindman noted.
"CT doses are sometimes higher than necessary."
The most common cancer types resulting from CT radiation, according to the study, include lung cancer, colon cancer, leukemia and breast cancer.
The study, which was published on April 14 in JAMA Internal Medicine, received funding from the National Institutes of Health.
"In many cases, CT is the most appropriate test for achieving rapid and accurate diagnoses," Smith-Bindman told Fox News Digital.
"However, the use of CT continues to rise, including a concerning increase in imaging that is performed without a justified medical reason — often referred to as ‘low-value scanning.’"
Based on the findings, the researchers recommend avoiding unnecessary CT scans to avoid potential harms.
Another risk-reducing approach is to lower the radiation dose per scan.
"CT doses are sometimes higher than necessary, so patients are encouraged to ask their healthcare providers or technologists to use the lowest possible dose for their scan," Smith-Bindman advised.
Ultimately, the researcher said, patients should have informed conversations with their healthcare providers about the necessity of a CT scan and whether alternative imaging options — like ultrasound or MRI — might be more appropriate.
"If CT is clearly indicated, the benefits far outweigh the risks," she said. "But if not, it’s best to avoid the scan altogether."
"Less can be more when it comes to good patient care."
Dr. Nicole Saphier, board-certified radiologist and Fox News medical contributor, was not involved in the study but commented on the risks and benefits of CT scans.
"I have long advocated for the judicious use of medical imaging, often citing that less can be more when it comes to good patient care," she told Fox News Digital.
"The recent study linking the ionizing radiation from CT scans to an increased risk of cancer underscores what many in the medical community have understood for years: while imaging is a powerful diagnostic tool, it is not without risk."
Saphier said the study may even underestimate the total number of cancers attributable to medical imaging.
"Many cases of medical intervention-induced cancers may go unrecognized due to long latency periods, the complex interplay of contributing factors and the fact they omitted radiation from image-guided procedures, x-rays and other forms of medical radiation from this study," she noted.
"As imaging use and medical interventions continue to rise — especially in younger populations — the cumulative radiation exposure over a lifetime becomes an increasingly important consideration."
That said, Saphier went on, CT scans and other medical imaging modalities — which are "fast and cheap" — save lives every day.
"The key is balance. Physicians must remain vigilant in weighing the benefits against the risks, and should always explore alternative modalities when appropriate, such as ultrasound or MRI, which do not use ionizing radiation," she said.
Informed decision-making is essential for both clinicians and patients, according to the doctor.
"We must continue to refine our protocols, limit unnecessary imaging and ensure we are using the lowest possible doses without compromising diagnostic quality," Saphier concluded.
"This is not a call to avoid CT scans — it is a call to use them wisely."
https://www.foxnews.com/health/common-medical-test-linked-cancers-study-suggests-use-them-wisely
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