Radiation from CT Scans May Cause More Than 100,000 Future Cancer Cases Per Year: Study

Previous estimates suggested radiation from CT scans may be responsible for nearly 30,000 new cancer cases annually, but these findings indicate CT Scans in 2023 alone may cause 3x that many cancer diagnoses in the future.

A new study warns that the regular practice of giving some patients computed tomography (CT) scans may now account for 5% of new cancer cases every year.

Computed tomography scans, also known as CT or CAT scans, are medical imaging techniques that use computers and X-ray radiation to help model internal organs, bones and soft tissue in greater detail than traditional X-ray machines have the ability to do.

Although the advancement of modern medicine allows these kinds of scans to help diagnose cancer in certain individuals, the technology also increases the risk of patients developing new cases of cancer. As the technologies have come to be used more often following the COVID-19 pandemic, patients are being exposed to higher levels of ionizing radiation across their lifetimes.

According to findings published in the journal JAMA Internal Medicine on April 14, more than 93 million CT scans are now being performed in the U.S. each year. However, exposure to the ionizing radiation from these scans could lead to more than 100,000 future cases of leukemia, lung, colon, breast and other cancers, just from exams administered in 2023 alone.

In the new study, a team of researchers set out to determine the number of cancers correlated to the yearly number of CT scans given to patients.

The researchers, led by Dr. Rebecca Smith-Bindman from the University of California, San Francisco, developed a risk model of CT scans linked to cancer. They analyzed data from a multicenter sample of CT examinations from January 2018 to December 2020 done at the University of California San Francisco International CT Dose Registry.

Of the 63 million patients who underwent CT scans, roughly 2.6 million were children and the rest were adults.

Researchers noted that radiation induced cancer risks were higher among children and teens, but the number of CT scans per patient was much higher among adults, which accounted for the most radiation induced cancers.

Overall, the most common cancers found were lung cancers, accounting for 22,000 of all cancer cases.

Following that, the most common cancers were colon cancer, accounting for 9,000 cases, leukemia, accounting for 8,000 cases, and bladder cancer, accounting for 7,000 cases. Among female patients, breast cancer was the second most common kind of cancer developed, accounting for 6,000 cases.

The data indicated CT scans in 2023 could account for more than 103,000 future cancer cases due to the exposure to ionizing radiation, a known carcinogen to humans.

The largest number of projected cancers stemming from exposure to CT scans was estimated to be abdomen and pelvis cancers, accounting for 37,000 or more than 40% of future cancers. Chest CT scans were estimated to account for 21,000 future cancer cases.

Head CT scans accounted for the largest number of projected cancers among children causing more than 5,000 cases or half of all projected cancers among that age group.

Researchers emphasized that if current CT scan numbers and radiation dosing practices continue, cancers associated from CT scans will eventually account for 5% of all new cancer diagnoses every year.

Risks of CT Scan Radiation

Researchers have long raised concerns about the risks of radiation exposure from CT scans, with a 2009 study estimating that annual CT scans may account for nearly 30,000 new cases of cancer each year.

Another study published by researchers from the University of California, Davis warned children may be undergoing far too many CT scans, which can lead to higher rates of cancer among that age group. Researchers found that reducing the highest 25% of CT doses doctors could prevent more than 40% of future cancers in children.

Additional research conducted by the U.S. Centers for Medicare and Medicaid Services echoes this finding among adults as well, warning that doctors often order unnecessary CT scans for adult patients, with patients often undergoing 100 to 500 times more radiation than necessary.

Moreover, a study published by the Denver Veterans Affairs Medical Center in 2013, warned that patients who undergo CT scans are not made aware of the levels of radiation exposure they face during those scans, increasing their risk of cancer and other health problems in the future.