CT Heart Scans Raise Cancer Risk
Study suggests the tests be carefully matched to patients' need, risk
TUESDAY, July 17, 2007 (HealthDay News) -- CT scan coronary angiography (CTCA), a test to determine the presence of heart trouble, can up the risk for cancer, especially for women and younger people.
The finding comes from a new study in which doctors sought to estimate lifetime cancer risk from CTCA for particular patients. It suggests that doctors should carefully evaluate which patients are the best candidates for this test.
"There are numerous diagnostic tests out there, so it's sort of a matching problem for clinicians, matching the appropriate patients with the appropriate diagnostic tests," explained Dr. Andrew J. Einstein, lead author of the study, which is published in the July 18 issue of the Journal of the American Medical Association.
This type of decision "always involves a risk-benefit balance for each of the various tests one is considering," he said.
However, the new study "gives us the ability to estimate for a given patient what the cancer risk is," added Einstein, who is an assistant professor of clinical medicine at Columbia University College of Physicians and Surgeons in New York City.
The findings weren't surprising, other experts said.
"We already knew that the test, as useful as it is and as terrific as the pictures are, did expose the patient to a lot of radiation," said Dr. Gregory Dehmer, director of the cardiology division at Scott & White Hospital in Temple, Texas. "I think this study is just going to confirm perhaps in a more elegant way what we already knew -- that there's a lot of radiation involved. The really important thing for the average clinician in this is to realize when it's appropriate and when it's inappropriate to do a CT angiogram."
Coronary artery disease (CAD), which occurs when the arteries supplying blood to the heart become hardened and constricted, is the leading killer of men and women in the United States, responsible for one in five deaths.
The gold standard for diagnosing CAD is coronary angiography, but this involves inserting a catheter into a blood vessel and can have serious complications. Physicians have been looking for noninvasive methods that can provide the same information. One of these is the CTCA, approved for use in 2004. This technology, which collects multiple images of the body, is both sensitive and specific.
"One particularly appealing use for CTCA is in the evaluation of chest pain patients in the emergency room," Einstein said. "There are about 6 million such patients each year and we want to get them through the system as quickly as possible, either to the cardiac catheterization lab if they are having a heart attack or unstable angina, or home as quickly as possible, as they take up beds in the hospital."
Little is known, however, about the risk of cancer from the procedure.
"There has always been this perception that the radiation risk of CT coronary angiography is relatively high, but clinicians didn't have a way to quantify that in their decision-making process," Einstein said.
Einstein and his colleagues used computer simulation to estimate the lifetime risk of cancer associated with radiation exposure from a 64-slice CTCA.
The lifetime cancer risk ranged from one in 143 for a 20-year-old woman to one in 3,261 for an 80-year-old man.
"A lot of people have suggested CT coronary angiography as a good test but if you have a patient who's young and female, it may not best test of choice. There may be other alternatives," Einstein said. "At the same time for older patients, the cancer risk is not so high compared to a great benefit, so it can be reassuring for many patients. The study enables one to take this 'black box' worry about radiation from a CT coronary angiogram and come up with more quantitative, patient-based information on what the risk is and enable better decisions about which patients should have the test ordered."
The bottom line, according to Einstein: "If you're having chest pain and are concerned you're having real coronary disease and the doctor thinks it's the best test, I wouldn't discourage it," he said. "If it can prevent a heart attack from occurring, it's certainly a good thing." On the other hand, he said, "I don't think we should be rushing to screening just for curiosity."
For more on coronary artery disease, visit the U.S. National Heart, Blood, & Lung Institute.