ACR Challenges Study Linking CT Scans to Increased Cancer Risk

The American College of Radiology (ACR) has raised concerns over a recent study published in JAMA Internal Medicine that suggests computed tomography (CT) scans could be responsible for up to 5% of all new cancer cases annually in the United States. The study, led by Dr. Rebecca Smith-Bindman of the University of California, San Francisco, analyzed data from approximately 93 million CT scans performed on 61.5 million patients in 2023. Using statistical models, the researchers projected that these scans could result in about 103,000 future cancer cases, with abdominal and pelvic CTs being significant contributors. 

In response, the ACR criticized the study's reliance on theoretical models rather than actual patient outcomes. They emphasized that no published studies have directly linked CT scans, even multiple ones, to cancer. The ACR highlighted that advancements in CT technology and optimized imaging protocols have reduced the population's radiation burden, despite increased CT usage. 

The study's authors acknowledged that while individual cancer risk from a single CT scan is low, the cumulative effect across the population could be significant. They noted that the per-exam risk is higher among children, but the greater number of scans performed on adults accounts for most projected cases. The most common forecasted cancers include lung, colon, leukemia, and bladder cancers.

Editorial commentary in JAMA Internal Medicine suggested that providers could mitigate risks by employing artificial intelligence to reduce unnecessary imaging, opting for alternative modalities that do not use ionizing radiation, lowering CT dosages, and educating clinicians about avoiding low-value imaging. 

The ACR, however, emphasized the life-saving benefits of CT imaging, stating that such exams are primary factors in declining cancer death rates and are directly linked to decreased hospital mortality and greater life expectancy. They also assist in reducing invasive surgeries, unnecessary admissions, and hospital lengths of stay. 

The ACR advises patients not to forgo necessary, life-saving medical imaging and encourages discussions with healthcare providers about the benefits and risks of these exams. They also recommend that patients keep a record of their imaging procedures to facilitate informed decisions.

This debate underscores the importance of balancing the diagnostic benefits of CT imaging with the potential risks associated with radiation exposure. Ongoing advancements in imaging technology and protocols aim to minimize risks while maximizing diagnostic efficacy.