In the United States, the number of computed tomography, or CT scans, performed each year has more than tripled since 1993 to approximately 70 million CT scans per year. People who undergo CT scans are exposed to more radiation than with conventional x-rays, so there is concern about potential future cancer risks.In the December 14/28, 2009 issue of Archives of Internal Medicine, scientists report on several types of CT scans that make large contributions to total cancer risk.

Researchers from the National Cancer Institute and their colleagues conducted detailed estimates of the future cancer risks from the current use of CT scans in the United States according to age, gender, and types of CT scans. Overall, the researchers estimated that approximately 29,000 future cancers could be related to CT scans performed in the United States in 2007. According to their risk models, the researchers estimate that the largest contributions to total cancer risk were from CT scans of the abdomen and pelvis, chest, and head, as well as from CT angiograms of the chest. One-third of the projected cancers were due to CT scans performed at the ages of 35 to 54 years and 66% of the projected cancers were in women.

The best way to evaluate the long-term cancer risks from CT scans would be to evaluate risk in very large-scale studies with lifelong follow-up. However, the risk projection models used in this study provide a more timely risk assessment. Even if the cancer risk associated with CT scans is small, the number of people who undergo CT scans each year could translate into a large number of future cancers. So, perhaps, the estimates reported in this study can help to inform patients and healthcare providers about the real risk of CT scans.

Source:

Arch Intern Med 2009;169(22):2071-2077.