February 28, 2013

By Rob Goodier

NEW YORK (Reuters Health) Feb 28 - Radiation exposure from CT scans may account for up to 2% of all cancers in the United States, but patients tend to underestimate their lifetime risk, a new study finds.

"I would recommend that providers optimize their own understanding of CT-related risk in order to best inform and educate their patients as they share in the decision to pursue such imaging studies," Dr. Margaret Cook-Shimanek, who led the study at the University of Colorado, Denver, told Reuters Health by email.

Dr. Cook-Shimanek presented her results February 21st at the annual meeting of the American College of Preventive Medicine in Phoenix-Scottsdale, Arizona.

A November 2007 review in the New England Journal of Medicine suggested that CT scans in the U.S. may be associated with 1.5% to 2% of all cancers.

But in the new study, 83% of the 271 radiology outpatients who participated underestimated their lifetime risk of death from one abdominal CT scan.

When patients were involved in making the decision to use the scan, they were less likely to underestimate the risk. Multivariate analysis found an odds ratio of 0.45 for those patients compared to others in this cross-sectional study.

Those who said, incorrectly, that radiation exposure is higher from MRI than from CT were more likely to underestimate the risk from CT scans (OR 2.26).

"Providing basic radiation education and involving patients in the decision to undergo CT scan may translate into better understanding of CT-related lifetime cancer death risk," Dr. Cook-Shimanek said.

This research was supported in part by a Physician Training Award in Preventive Medicine from the American Cancer Society (ACS) and in part by Health Resources and Services Administration (HRSA) Grant to the University of Colorado Preventive Medicine Residency Program.