Heart X-ray raises cancer risk for young, women

WASHINGTON, July 18 (Reuters) A special type of X-ray used to diagnose heart disease may cause cancer in women and young adults and should be used with caution, US doctors reported.

The procedure, called a computed tomography (CT) coronary angiography, is meant to reduce complications because it can see inside the heart and its arteries without invading the body.

But it gives a high dose of radiation, enough to cause cancer in vulnerable people, the researchers reported yesterday in the Journal of the American Medical Association.

They said women and young men are especially at risk.

''The same amount of radiation appears to be more likely to cause cancer in woman than in men,'' Dr Andrew Einstein, cardiologist at Columbia University Medical Center who led the study, said in a telephone interview.

''A second difference between women and men is the risk of breast cancer. The heart sits in the chest right behind the breasts so the breasts end up being irradiated.'' Younger people are more at risk in part because it can take years for cancer to develop after radiation damage, Einstein said.

The researchers found that a 20-year-old woman had a 1 in 143 lifetime risk of developing cancer from one of the scans. An 80-year-old man would have a 1 in 3,261 risk, they found.

A 60-year-old woman would have a 1 in 715 risk of cancer while a 60-year-old man would have a 1 in 1,911 risk.

The CT angiography is sometimes used in emergency rooms when someone comes in with chest pain and doctors need to assess quickly whether a heart attack is likely, Einstein said. He said 6 million patients come into US emergency rooms alone with chest pain every year.

''We are still trying to find out what the role of CT coronary angiography is,'' he said. ''I think it may not be the test of choice for young women.'' Einstein's team used a report last year from the National Research Council, an independent body that advises the federal government, that looked at the effects of low-level ionizing radiation on health.

They tested the CT angiography to see how much radiation it actually delivered. They combined their findings with the report on radiation to estimate the risks to patients.

The most common way to see if someone had clogged arteries is a standard angiogram, which uses a standard X-ray.

The doctor uses a catheter to inject a chemical called a contrast agent that makes the arteries easier to image, and this process can cause side effects as it involves punching a hole in an artery.

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