CT Scans May Contribute to 5% of Annual Cancer Cases, Study Suggests

CT scans now rival known cancer risk factors like alcohol and obesity

CT Scans May Contribute to 5% of Annual Cancer Cases, Study Suggests

DECK
Millions exposed to radiation through routine medical imaging; experts call for more cautious use amid comparisons to alcohol and obesity as cancer risks.

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KEY FACTS

• What: New study estimates CT scans could cause 103,000 future cancers.

• When: Based on 2023 CT scan data, published in JAMA Internal Medicine.

• Where: United States; data analyzed from 93 million scans on 62 million people.

• Why: Ionizing radiation from CT scans linked to increased cancer risk.

• How: Study modeled cancer projections by scan type and organ exposure.

• Concerns: CT scans now rival known cancer risk factors like alcohol and obesity.

• Response: Experts urge smarter use, dose reduction, and alternative imaging options.

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SITUATION SNAPSHOT
Hospitals and clinics across the U.S. conduct over 90 million CT scans every year—vital tools that diagnose everything from internal bleeding to tumors. Yet behind the high-speed imagery lies a quieter risk. Researchers now warn that the very scans saving lives could, in some cases, be setting the stage for future cancer diagnoses.

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WHAT WE KNOW
A recent study led by researchers at the University of California, San Francisco estimates that CT scans performed in 2023 may eventually lead to around 103,000 cancer cases. That figure represents approximately 5% of annual cancer diagnoses in the U.S. if current practices continue. Most projected cases involve lung and colon cancers, with abdomen and pelvis CT scans posing the highest risk.

"CT is frequently lifesaving, yet its potential harms are often overlooked, and even very small cancer risks will lead to a significant number of future cancers given the tremendous volume of CT use in the United States," the authors stated.

Experts emphasize that CT scans should only be used when medically necessary and delivered at optimized doses. While previous studies have shown links between radiation exposure and cancer—particularly in children—the risk to adults has typically been modeled from populations exposed to radiation from events like the atomic bomb or occupational settings.

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WHAT’S NEXT
Medical professionals are expected to reevaluate how often CT scans are prescribed. Some are urging greater use of diagnostic alternatives such as ultrasound and MRI, both of which avoid ionizing radiation.

An editorial accompanying the study encourages doctors to rethink low-value testing and involve patients in decisions when non-radiative imaging is an option.

"As with all complex problems, there will be no simple solution," the editors wrote. Still, small shifts in diagnostic culture may have a lasting impact.

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VOICES ON THE GROUND
"The estimates, while based on the best models available to the authors, are indirect, so there is considerable uncertainty about the estimates," said Stephen Duffy, emeritus professor of Cancer Screening at Queen Mary University of London. "Thus, I would say to patients that if you are recommended to have a CT scan, it would be wise to do so."

"This amounts to around a 0.1 percent increase in cancer risk over the patient's lifetime per CT examination," he added, underscoring that CT scans offer vital benefits that often outweigh the risks.

"The findings don’t mean that people should avoid CT scans when recommended by a doctor," said Doreen Lau, a cancer biology expert at Brunel University of London. "In most cases, the benefit of detecting or ruling out serious illness far outweighs the very small risk of harm."

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CONTEXT
CT imaging is deeply embedded in modern healthcare. According to an accompanying editor’s note, the technology is "inextricably woven into the fabric of modern medicine." Its speed, accuracy, and affordability have made it indispensable in diagnosing trauma, cancer, and countless other conditions.

Yet, the editors say the findings should be a wake-up call. They place CT scan-related cancer risks in the same tier as lifestyle-related risks such as alcohol and obesity. Recommendations include expanding the use of radiation-free imaging tools, reducing scan doses, and educating clinicians to avoid unnecessary tests.

This isn’t a new concern. A 2015 Consumer Reports investigation estimated that up to one-third of CT scans might be unnecessary—exposing patients to needless radiation.

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REPORTER INSIGHT
From emergency rooms to cancer clinics, CT scanners hum around the clock, often acting as the first line of defense in urgent care. But as the machines do their work, the quiet accumulation of radiation risk grows too. This report reminds us that even life-saving tools require thoughtful oversight—and that informed choices by both doctors and patients are essential in balancing benefit with long-term safety.