Excessive CT Scans May Raise Cancer Risk Similar to Alcohol and Obesity: Study Warns

New Delhi: Repeated and unnecessary exposure to computed tomography (CT) scans could significantly raise the risk of developing cancer—on par with well-known risk factors such as alcohol consumption and obesity—according to a new study by researchers at the University of California-San Francisco (UCSF). The findings, published in JAMA Internal Medicine, reveal that radiation from CT scans may account for nearly 5% of all annual cancer cases.

The study analyzed data from 93 million CT scans performed in 2023 across the United States, covering 61.5 million patients. Based on this data, the researchers estimate that approximately 103,000 cancer cases could arise from radiation exposure, a figure three to four times higher than previous estimates.

Lead author Dr. Rebecca Smith-Bindman, a radiologist at UCSF, emphasized that while CT scans are an essential diagnostic tool capable of saving lives, their potential long-term harm is often underappreciated. “CTs can be life-saving, but the radiation they emit is a carcinogen, and overuse or high doses carry significant risks,” she said.

The study identified infants, children, and adolescents as especially vulnerable, with those under one year of age facing the highest risk. While children made up only 4.2% of the total scans, the projected risks were still significant. In children, the cancers most associated with CT radiation exposure were thyroid, lung, and breast cancers. Among adults, the most common projected cancers included lung, colon, leukaemia, bladder, and breast cancers.

The number of scans increased with age, peaking in individuals aged 60 to 69. The researchers stressed the urgent need to reduce both the number of scans and the radiation doses used per scan. "Doing so could prevent thousands of cancer cases and save lives," said Dr. Smith-Bindman.

Given the widespread reliance on CT technology, the study underscores the need for more judicious use—particularly in pediatric populations—and for greater awareness of its long-term risks, aligning it with other modifiable cancer risk factors like obesity and alcohol.