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Breast cancer and radiation

Posted by medconsumers on June 13, 2012

Want to know the best way to reduce your chances of developing breast cancer? Avoid inappropriate CT scans of the chest. This is the refreshingly blunt conclusion of a new study funded by the U.S. National Cancer Institute. The radiation exposure from this imaging procedure is huge,  the damage is cumulative, and the breast is known to be one of the most radiation-sensitive organs of the body. There has been an alarming five-fold increase in the use of CT scans over the last two decades.

CT scans of the chest are ordered for diagnosing diseases of the heart, the lungs, and even screening symptomless people for these diseases. And it is not yet clear whether the improvements in diagnostic accuracy outweigh the cancer-causing harm of radiation exposure.

Among the reasons given for the inappropriate use of CT scans are: financial incentives, especially for hospitals and physicians who own their CT equipment; expanding indications for appropriate use; fear of malpractice lawsuits; and public demand fostered by hospital advertising campaigns. Too often, radiation exposure is unnecessarily high due to poorly trained technicians, the lack of universally agreed-upon standards for minimal exposure, and failure to calibrate the scanning equipment to the size of the patient.

The National Cancer Institute-funded study was conducted by Rebecca Smith-Bindman, MD, a professor of radiology and biomedical imaging, epidemiology and biostatistics at University of California, San Francisco, and published yesterday online in the Journal of the American Medical Association (JAMA).  She has focused on the breast because of an Institute of Medicine report that was published at the end of last year. Commissioned by the high profile foundation called Susan G. Komen for the Cure, this report disappointed many breast cancer advocates who wanted to know which pesticides and toxic substance in consumer products are the most likely to cause breast cancer.

The Institute of Medicine found insufficient evidence for any of these potential health hazards, but singled out “avoidance of medical imaging as one of the most important and concrete steps that women can take to reduce their risk of breast cancer.” Dr. Smith-Bindman used the National Cancer Institute funding to document the rise in CT scanning between 1996 and 2010 based on the care of patients at six U.S. health plans with 1-2 million enrollees altogether. She found a tripling of the number of CT scans, and a doubling of per capita radiation dosage over the study period. It should be noted that this finding could understate the magnitude of the problem because physicians practicing in managed health plans do not have a financial incentive to overdo the ordering of tests.

Acknowledging the media attention given previous studies documenting CT scan overuse, Dr. Smith-Bindman noted in an online video provided by JAMA: “There is a belief that we’ve solved the problem about radiation dose due to increased awareness over the years, but I’m not convinced that we’ve gotten the doses down, particularly in children and young adults, which are much higher than I would like to see.”

People should ask for the radiation dose before agreeing to a CT scan and make sure the dose is listed in their medical records, she advises, hoping that a groundswell of consumers asking pointed questions will improve the current situation. “Many ordering physicians are insufficiently informed about radiation doses and the cancer risks attributable to medical images,   and yet this information is crucial to weigh risks and benefits and provide appropriate justification for the use of CT and other high-dose imaging studies to patients and families.” Testifying before Congress last week about radiation safety, Dr. Smith-Bindman reportedly said, “Some people have worried about the X-rays at our airports to screen passengers, but one CT scan is equal to approximately 200,000 airport screens.”

When this study was reported yesterday by Medpage, an information source for physicians and journalists, one of the first comments came from an anonymous expert who appears to be a medical physicist, which is a specialist in the health effects of radiation on the human body:

“One issue is the variation in image quality caused by differences in expertise and experience amongst equipment operators, maintenance and calibration protocols, and servicing intervals. Another is the variation in image quality caused by the use of older versus newer, mid-range versus high-end equipment. When I researched this area in some depth about ten years ago, I discovered that the top-end equipment was being built by Japanese firms and only being used in Japan. It simply wasn’t available in the USA, in the EU or elsewhere. I have yet to speak to a specialist in medical imaging technology, or a pathologist or oncologist, let alone a typical medical generalist, who has more than an entry level understanding of the medical physics employed in this area. Accurate images, taken from multiple angles, can be a real boon. But the average physician doesn’t know how to interpret them, and most radiologists refuse to discuss medical imaging results directly with patients.

And another comment from the same Medpage forum:

“For each non-emergency situation, ask your physician or dental  professional, ‘Is this imaging procedure going to change the  treatment plan?’  If they can’t provide an intelligent answer,  then I refuse or delay the test until I speak to someone who can.   Every time my <10 yr old child goes to the Orthodontist, the  assistant immediately says, ‘let’s get some x-rays’ (or even a whole  facial scan) and then gets mad when I question her.  They’ve never  actually recommended any treatment/action taken for my child’s  teeth; she is just being observed yearly so why take x-rays  additional to the ones she has at the regular Dentist?  On the  other hand, my ~40 yr old husband hit his head tubing in the  Smokies.  At the ER, I agreed on a head CT because having a brain  bleed, although highly unlikely, could be fatal.  So, each patient  needs to question the risk to benefit ratio and consider age at the  time of exposure.”

Maryann Napoli,Center for Medical Consumers(c)
Related posts:
Tests to avoid CT scans appear frequently on the specialists’ list of inappropriate tests.
CT scans: lots of radiation, little research Explains why CT Scan radiation dose is so much higher than that of a conventional x-ray. And how to determine when a scan may be inappropriate.
Another way to cut your risk of breast cancer:  Explains how mammography screening  increases your chances of  being  diagnosed with breast cancer and  treated unnecessarily for a cancer that did not need to be detected.

2 Responses to “Breast cancer and radiation”

  1. TeresaM said

    Thank you so much for this report. It’s so clear and a little shocking to me. I am very careful with consumer products – and will continue to be careful – but I’m encouraged to hear that no risk is yet associated with them. The CT scans on the other hand… I’ve had a couple in my life that I would have avoided had I known the risk.

    Do you believe this implies that all screening x-rays should be avoided in general? My dentist takes x-rays annually (which I’ve never liked.) At least they are very focused.

    Have you heard of any related studies with respect to x-rays at airports?

    • The Institute for Medicine was asked to determine whether any of the potential toxins in the environment cause breast cancer. “Insufficient evidence” answers only that very narrow question. Sorry but haven’t kept up with the advice on screening dental x-rays. Some experts in radiation exposure think that screening CT scans should be avoided entirely because of the large amount of radiation (low-dose lung scans are the exception) and the fact that they are performed on healthy symptomless people. In 2009, the American Heart Association acknowledged that the amount of radiation from a heart scan is equivalent to 600 chest x-rays. Re the other type of screening, the kind done at airports, see the above quote from Dr. Smith-Bindman.

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