CT Scan Radiation May Cause Cancer for 29,000 People Each Year: Study

Researchers in two new studies are raising serious concerns about the effects of radiation from CT scans, with some estimating that about 29,000 Americans will develop cancer later in life and 15,000 will die as a result of scans performed in one year.

The studies were published on Monday in the Archives of Internal Medicine. One study, lead by researchers from the National Cancer Institute, looked at projected cancer rates among people who received computed tomographic (CT) scans. The other study, led by a University of California researcher, was an analysis of the radiation doses associated with CT scans and cancer risks. Both studies found that cancer rates and the doses of radiation patients receive are often higher than expected.

The new findings come at a time when CT scan procedures across the country are under close scrutiny by the FDA after the discovery that a number of patients have suffered radiation overexposure from CT Scans performed incorrectly. The FDA is currently reviewing CT scan procedures nationwide, and released interim guidance for health care professionals and radiologists last week. The guidance advised them to review procedures and CT scan settings, and to be thorough in checking the amount of dosage prescribed for each CT scan patient.

The National Cancer Institute study looked at Medicare claims and information from the IMV Medical Information Division survey of CT scan use in 2007, among a number of other data sources. The survey looked at usage in 2,451 facilities across the United States. Researchers estimate from their findings that there are 70 million CT scans annually.

CT scan radiation could be responsible for as much as 2% of all cases of cancer in the U.S., according to researchers. It is estimated that 29,000 people annually could develop cancer within five years of receiving a scan and about half of those people will die from the cancer. The study’s results suggest that the risk of cancer decreases with age, so that a younger person receiving a CT scan has a much higher risk of developing cancer later in life than someone significantly older.

The University of California study was a retrospective cross-sectional study of CT scans performed on 1,119 adults in San Francisco facilities between January and May of 2008. Researchers found a high amount of variation between radiation doses, with some radiation exposure varying as much as 13-fold between scans. The study estimated that 1 in 270 women who received a CT heart scan would develop cancer, compared to 1 in 600 men.

Researchers in that study also found that the cancer risk decreased with age.

Scientists in the National Cancer Institute recommended that the risk of cancer could be lowered by decreasing both the number of unnecessary CT scans and by decreasing the radiation doses per scan. Researchers from the other study recommended that there be an industry-wide standardization of radiation doses for different types of CT scans.