Radiation from computerized-tomography scans may cause cancer decades later, according to a study that estimated about 29,000 future malignancies would occur in the U.S. because of CT scans done in 2007.
Most of the cancers are predicted to strike women, who receive more CT scans than men, and about one-third of the projected malignancies may occur from scans performed in people ages 35 to 54, said research published Monday in the Archives of Internal Medicine.
The cancer forecast was based on an estimate that about 72 million CT scans were done in 2007.
The number of CT tests in the U.S. has tripled since 1993, according to the study. More research is required to determine the lowest dose of radiation needed for clear pictures from CT scans to help reduce radiation exposure, said lead study author Amy Berrington de Gonzalez.
“We know that there are great medical benefits to CT scans, but they also involve small risks of cancer because of radiation exposure,” said Berrington de Gonzalez, a researcher at the National Cancer Institute in Bethesda, Md. “For an individual, the risks are small. So if the scan is clinically justified, then the benefits should outweigh the risks.”
She said said the overall risk for any individual depends on the type of scan given and a person’s age. A 70-year-old who has a CT scan of the head would have a 1-in-10,000 chance of developing cancer from the test, while a baby who had a chest CT scan would have a 1-in-200 chance, she said.
The authors predicted lung cancer will be the most common radiation-created cancer, followed by colon cancer and leukemia.
