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New Heart Scans Pose Small Cancer Risk

Posted Dec 01 2010 5:31pm

Wednesday, December 1, 2010
  Reuters Health Information Logo

By Lynne Peeples

NEW YORK (Reuters Health) - The added cancer risk from undergoing state-of-the-art heart scans may be trivial, according to Greek researchers.

Over a lifetime, they estimate, about one in 4,000 women who've had their hearts examined once with the latest generation of computed tomographic (CT) scanners would develop cancer as a consequence.

Among men, the risk was less than one in 13,500. By comparison, about one in three Americans develop some type of cancer during their life.

While the finding could ease concerns about the growing use of CT scans and the extra radiation that entails, the researchers still recommend that patients and their doctors always consider whether a test is really necessary.

"This shows us that radiation doses and cancer risks are coming down in (heart imaging) when we use some of the newer technologies now available," Dr. Andrew Einstein of the Columbia University Medical Center, who was not involved in the study, told Reuters Health. "That's a good thing."

CT scans are a non-invasive and precise way to image the heart's arteries. The newest scanners expose patients to far less x-ray radiation than older machines by monitoring the heartbeat and turning the beam on and off during the scan, explained Einstein.

Based on a study of 136 patients who underwent heart scans, John Damilakis of the University of Crete and his colleagues calculated the cancer risks linked to the radiation patients received.

More than 90 percent were scanned with the most advanced machines and with the latest x-ray trimming technique, called prospectively gated CT.

The remaining patients received three to four times as much radiation during scans with the older machines.

The researchers say women probably had a higher cancer risk because of the sensitivity of breast tissue to radiation. However, they still found that lung cancer was the more likely cancer among both men and women.

The cancer risks also appeared to vary based on body size and dropped with age at the time of testing, report the researchers in the journal Circulation.

"For this reason, we suggest personalized risk assessment," Damilakis told Reuters Health in an email.

"It only makes sense to expose a patient to any risk, however small, when the patient can be expected to derive a benefit from the procedure," Dr. Reza Fazel, of the Emory University School of Medicine, told Reuters Health in an email. "When these procedures are used appropriately, the benefit typically far outweighs the cancer risk."

For example, the researchers note that the lifetime risk of developing coronary artery disease after age 40 is more than 50 percent for men without symptoms.

"If a patient is in the emergency room and needs to get one of these CT scans because it's important for their health, I don't think they should be overly concerned about radiation dose and avoid a potentially life-saving diagnosis," said Einstein.

"But if a patient is having chest pain as an outpatient and has a choice of facilities to go to," he added, "then it would be reasonable to ask around to see whether some of the newer technologies such as (advanced CT scans) are available."

Another study published in the same edition of Circulation addressed the potential cancer risks associated with another heart diagnostic tool: the myocardial perfusion scan, an advanced type of stress test.

Although the scan accounts for as much as 20 percent of the total estimated annual radiation dose in the U.S. population, the lifetime risk of developing cancer from one scan is small.

Depending on the specific type of scan, there would be an estimated 2 to 25 extra cases of cancer per 10,000 scans performed.

This contrasts with other recent research, which raised concerns about relatively high radiation doses with the tests. (See Reuters Health story of November 15, 2010.)

"The American Heart Association and the American College of Radiology have published guidelines describing when it is most appropriate to use these tests," lead researcher of the new study on the stress tests, Amy Berrington de Gonzalez, told Reuters Health in an email.

In general, if the tests are appropriate, de Gonalez, of the National Institutes of Health in Bethesda, Maryland, suggested that the "benefits should outweigh the small individual risks."

SOURCES: http://link.reuters.com/byr97q and http://link.reuters.com/cyr97q Circulation, online November 22, 2010.

Reuters Health


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