CT scans may trigger more than 100,000 new cancer cases

The 60 million Americans who had CT scans last year could face disturbing future consequences – cancer. A comprehensive new study published on Monday JAMA Internal Medicine The forecast for the 93 million CT tests conducted in 2023 will ultimately result in about 103,000 cancer cases in the patient’s lifetime.

If the current practice continues, the radiation from these medical imaging programs may eventually account for 5% of all new cancer diagnoses each year, CT scans comparable to alcohol consumption.

Dr. Rebecca Smith Hindman of the University of California, San Francisco, who led the research team analyzed data from more than 120,000 actual CT exams from 143 hospitals and outpatient facilities in 20 states.

“CT often saves lives, but its potential harm is often overlooked, and even a small risk of cancer can lead to future cancer, as CT is used in the United States in a large amount,” the researchers wrote in the study results.

The study represents a sober update of the 2009 analysis, which estimates 29,000 future cancers in CT scans performed in 2007. The new projection is three to four times, reflecting an increase in CT utilization and more precise radiation dose modeling.

Children face higher risks

Although only 4.2% of CT recipients are children, the risk of cancer is significantly higher per checkup. The study found that the cancer risk for girls under one year old is 20 cancers per 1,000 tests, while only 2 cancers among teenage girls aged 15-17.

Despite the increased risk in younger patients, the huge scan volume in adults means 91% of the expected cancer will occur in the adult population. Adults in their 50s face the highest burden, and CT scans in this age group are expected to cause about 19,700 future cancers.

Thyroid cancer accounts for more than one-third of the estimated childhood cancers of CT exposure, while lung cancer represents the biggest concern for adults.

Not all CT scans have the same risk

Among adults, abdominal and pelvic scans pose the greatest risk of cancer, resulting in 37,500 projected cases, more than one-third of the total. These scans typically employ multiple imaging stages, which can significantly increase radiation exposure.

“These tests can often use single-phase scans, which will reduce the dose without affecting diagnostic accuracy,” the researchers noted.

Chest CT follows the second highest risk category, with 21,500 cancers expected. Head CT usually involves lower radiation doses to key organs, but due to its frequency, children cause the most cancer cases in children.

Overall, four cancer types represent the majority of the estimated cases: lung cancer (22,400), colon cancer (8,700), leukemia (7,900), and bladder cancer (7,100). Among women, breast cancer is the second most common radiation-induced cancer.

Finding a balance

The authors of the study acknowledge the important medical value of CT imaging, but emphasize the need for caution. CT utilization has increased by 35% since 2007, an increase that cannot be explained by population growth alone.

“Reasons for use and optimization of doses, including considering the need for multiphase examinations, are the purpose of CT imaging and must be used without compromise to mitigate potential harm,” the researchers concluded.

These findings highlight the ongoing challenges for healthcare providers: balancing high-quality medical imaging with direct diagnostic benefits of long-term radiation risks. For patients, the results highlight the importance of discussing with healthcare providers whether CT scans are really necessary or appropriate.

The research team conducted extensive sensitivity analysis, and cancer prediction ranged from