CT Scans and Cancer Link: Study Shows CT Scans May Cause Cancer
Two studies found the link between CT scans and cancer risks. One study projected the 70 million CT scans performed in 2007 can lead to 29,000 future cancers. The risk associated with CT scans is higher than expected, and if validated, its use will be greatly decreased. Doctors must consider if the risk of CT scans outweigh the potential benefits. Robert Smith, director of cancer screening for the American Cancer Society, urged the public not to misinterpret the result of the new studies:
"As striking as these numbers are, we need to address this issue with common sense. It is important that patients not refuse a CT scan when one is indicated."
"They remind us that the potential benefits of a CT scan have to outweigh the possibilities of harm."
Radiation doses from computer tomographic (CT) scans range from 2 mSv to 31 mSv. One mSv is the amount of background radiation absorbed by an average American in a year.
In the first study, based on information from four San Francisco-area hospitals, median effective doses ranged from 2 mSv for a routine head scan to 31 mSv for a multiphase abdomen and pelvis scan, according to Dr. Rebecca Smith-Bindman of the University of California San Francisco, and her colleagues.
The use of diagnostic CT scans have increased dramatically, from 3 million scans in 1980 to 70 million in 2007.
One study calls for standardized procedure because the same procedure performed at different institutions, or different machines at the same hospital, can yield a 13-fold difference in radiation doses.
In one study, researchers from UC San Francisco found that the same imaging procedure performed at different institutions -- or even on different machines at the same hospital -- can yield a 13-fold difference in radiation dose, potentially exposing some patients to inordinately high risk.
To put the radiation dosage in perspective, a normal chest CT scan is equivalent to around 100 X-rays, but the researchers found some scanners give an equivalent of 440 X-rays.
CT scans provide clear views of internal organs by combining multiple X-ray images. It is often used to find hidden tumors or other illnesses. However, as the new studies show, the scan itself can cause the very illness it tries to identify.