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Unnecessary medical radiation driving up U.S. cancer rates, two physicians say

Medical imaging can be life-saving, but it also can be dangerous.

The 4 million CT scans given each year to children in the United States under the age of 15 may result in almost 5,000 future cases of cancer.

“We are silently irradiating ourselves to death.”

That’s the conclusion — and warning — that cardiologist Dr. Rita F. Redberg and radiologist Dr. Rebecca Smith-Bindman, both of the University of California, San Francisco, make in a commentary article published last Friday in the New York Times.

In the article, Redberg (who is also chief editor of the journal JAMA Internal Medicine) and Smith-Bindman note how the use of medical imaging with high-dose radiation — particularly computed tomography (CT) scans — has skyrocketed during recent years. In 2006, Americans received six times more medical radiation then they did in 1986.

Such imaging can, of course, be lifesaving, but it also can be dangerous. Tests that deliver a high dose of ionizing radiation are associated with a significant increased risk of developing cancer later in life.

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A risk-benefit analysis needs to be done, therefore, before a patient undergoes a CT scan. But, unfortunately, physicians and hospitals all too often order the tests for medically unnecessary reasons.

Future cancers

“While it is difficult to know how many cancers will result from medical imaging,” write Redberg and Smith-Bindman, “a 2009 study from the National Cancer Institute estimates that CT scans conducted in 2007 will cause a projected 29,000 excess cancer cases and 14,500 excess deaths over the lifetime of those exposed. Given the many scans performed over the last several years, a reasonable estimate of excess lifetime cancers would be in the hundreds of thousands.”

Another study, which I reported on here last year, found that the 4 million CT scans given each year to children in the United States under the age of 15 may result in almost 5,000 future cases of cancer.

“According to our calculations,” write Redberg and Smith-Bindman, “unless we change our current practices 3 percent to 5 percent of all future cancers may result from exposure to medical imaging.”

A need for more protections

CT scans are widely acknowledged as being overused in the United States, which is why, as Redberg and Smith-Bindman point out, the American College of Radiology and the American College of Cardiology have issued “appropriateness criteria” to help physicians weigh the risks and benefits of the test before ordering it.

But many physicians do not follow those criteria. “For example,” write Redberg and Smith-Bindman, “emergency room physicians routinely order multiple CT scans even before meeting a patient. Such practices, for which there is little or no evidence of benefit, should be eliminated.”

But, even when the tests are appropriately ordered, patients may not be receiving the safest radiation dose possible because, as the two physicians point out, “there are no specific guidelines for what these doses are, and thus … the dose at one hospital can be as much as 50 times stronger than at another.”

Questions to ask

Redberg and Smith-Bindman call on the Food and Drug Administration to improve its oversight of medical imaging and for physicians to stop ordering unnecessary tests.

But “patients have a part to play as well,” they add.

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Before agreeing to a medical imaging test, they say, you should ask the following questions:

  • Will the test lead to a better treatment and outcome?
  • Would you get that treatment without the test?
  • Are there alternative imaging tests that don’t involve radiation, such as ultrasound or magnetic resonance imaging (MRI)?
  • When a CT scan is necessary, how can radiation exposure be minimized?

Redberg and Smith-Bindman also recommend that you check out the Choosing Wisely website to learn about the most common situations in which CT scans (and other medical tests and procedures) are overused. Other good resources are the Image Wisely (for adults) and the Image Gently (for children) websites. Both of these initiatives are aimed at raising awareness about the need to reduce unnecessary exposure to medical radiation.

In 2012, the Minnesota Department of Health became the first state health agency in the country to endorse the two “Image” initiatives.

You can read the New York Times commentary by Redberg and Smith-Bindman on the newspaper’s website.