Writing last month in the New York Times, Dr. Rita F. Redberg, a cardiologist, and Dr. Rebecca Smith-Bindman, a radiologist, applauded the advances made in preventing and treating cancer. But they also deplored the fact that the rate of cancer “remains stubbornly high and may soon surpass heart disease as the leading cause of death” in the U.S.
Even more alarming to patient safety advocates, their essay, “We Are Giving Ourselves Cancer,” suggests that the reason for cancer’s intractability might be our own fault; we are, they say, “silently irradiating ourselves to death.”
As we have written before, the growth in the use of diagnostic imaging, particularly technology such as CT scans that use high doses of radiation, presents the real risk of overexposure. Redberg and Smith-Bindman, of the University of California, San Francisco Medical Center, note that, between the 1980s and 2006, our exposure to medical radiation has increased sixfold. They say that radiation from a CT scan, which uses multiple X-rays to put together an image, can be 1,000 times higher than a conventional X-ray.
Like all medical procedures, the right one used at the right time can save your life. But the wrong one, or the right one used inappropriately, can present unnecessary risk. The harm from overuse of high-dose radiation imaging, according to the writers, is due simply to the fact that radiation is a carcinogen.
“A single CT scan exposes a patient to the amount of radiation that epidemiologic evidence shows can be cancer-causing,” they write, referring to several studies. In one, children exposed to multiple CT scans were found to be three times as likely to develop leukemia and brain cancer. Another concluded that radiation from medical imaging and hormone therapy were the leading environmental causes of breast cancer, and advised that women reduce their exposure to unnecessary CT scans. (Since that 2011 report, hormone therapy has declined.)
One in 10 Americans, say Redberg and Smith-Bindman, receive a CT scan every year. Many get multiple scans. Much of this inappropriate traffic is due to advertising the technology directly to consumers, and the pocket-lining practices of doctors who have financial interests in imaging centers.
CT technology is expensive, so any facility or person who has invested in it wants to use it.
If you can’t quantify the cancer caused by medical imaging, you can estimate it. The writers refer to a 2009 study by the National Cancer Institute projecting that CT scans performed in 2007 will cause 29,000 excess cancer cases, and 14,500 excess deaths among the patients who had them.
“Given the many scans performed over the last several years,” Redberg and Smith-Bindman write, “a reasonable estimate of excess lifetime cancers would be in the hundreds of thousands. According to our calculations, unless we change our current practices, 3 percent to 5 percent of all future cancers may result from exposure to medical imaging.”
Overuse aside, the doctors say that even when imaging is appropriate, it’s not always performed safely. Like the administration of medicine, the administration of radiation should reflect the lowest dose possible to achieve the desired result. But there is no universally accepted lowest dose standard, so what a patient gets depends on the facility where he or she is getting it. “The dose at one hospital,” the writers say, “can be as much as 50 times stronger than at another.”
And sometimes, the writers say, those measures can vary within the same facility.
One New York hospital the writers studied gave 1 in 3 of its cardiac patients imaging tests with the cumulative equivalent of radiation from 5,000 chest X-rays. And best practice for stress tests is to image a resting heart only after doing so during exercise. But one survey of nuclear cardiologists showed that only 7 in 100 such scans were performed before deciding whether it was necessary to image it at rest – that can decrease radiation exposure by as much as three-quarters.
The American College of Radiology and the American College of Cardiology have issued “appropriateness criteria,” the writers note, to inform doctors about the risks and benefits before ordering a test. And some health insurers scrutinize CT scan orders before authorizing payment for them. So the use of routine, unnecessary medical imaging has begun to slow.
But the danger of too much radiation is still a large problem whose resolution comes only by avoiding unnecessary scans and minimizing the radiation used for appropriate scans.
Redberg and Smith-Bindman call for better monitoring of and guidelines for radiation use. The FDA, they point out, oversees the approval of scanners, but lacks regulatory oversight for how they are used. They call for clear standards devised by professional radiology societies or organizations like the Joint Commission, a health-care certifying and accrediting agency, or the FDA.
Hospitals and imaging facilities shouldn’t be accredited to perform unless they record the doses they use and ensure that they are as low as possible by comparing them to published guidelines.
An ER visit, for example, often begins with the doctor routinely ordering multiple CT scans, sometimes without even seeing the patient first. If this happens to you or a loved one, question it.
The Times writers agree that consumers have a strong role to play in fixing this problem. They invite you to visit the Choosing Wisely website to learn about the most commonly overused tests, and before you agree to a CT scan, they say you should ask:
- Will it lead to a better treatment and outcome?
- Would you get that therapy without the test?
- Are there alternatives that don’t involve radiation, like ultrasound or MRI?
And if a CT scan is necessary:
- How can radiation exposure be minimized?
To read more about the dangers of radiation, see our backgrounder.