Do you know the risk?November 2001
As a screening device for breast cancer, CT scans do not work. Some radiologists are alarmed that women might think a chest or body scan can replace a mammogram. There are many differences between a CT scan and a mammogram. Mammograms were designed specifically for screening the breasts. They have a history of development and refinement behind them. They use far less radiation (200 millirads, or approximately eight chest x rays), and they reveal far more. While CT scans can be used for guiding breast biopsies, they are not a good screening device for breast cancer.
Unlike CT scan centers which are regulated by the state only, mammogram facilities have to be certified by the FDA. They must use the lowest radiation possible and they must retain radiologists who read at least 480 mammograms a year and attend continuing education classes. Radiologists who read mammograms have a lot of experience in looking for breast cancer.
Most people don't think about what will happen after the scan. But according to a Wall Street Journal report, one scan center sends 80% of its scanees to specialists post-scan. Either a whole lot of people are very sick or scan centers really don't know what they're doing. Stanley points to comments like one recently attributed to the director of a scan center who said that he's never seen a normal body scan-to argue that something is wrong with what they're doing. "Their motivation is misdirected," he argues. CT scans, he says, were never intended to be used without contrast material in asymptomatic people. Scans used in this way can reveal all sorts of "abnormalities". "When you're looking for abnormalities millimeter-by-millimeter, you're going to find them," he says. A person may go through thousands of dollars of unnecessary and invasive tests after a scan, including more radiation, to find out they have. . . nothing. It's like believing every mole on your body is melanoma. Stanley points out that if you take anyone who has died and section their kidneys millimeter-by-millimeter, in 22% of them you will find renal tumors. (A similar situation exists in the liver where "cavernous angiomas" develop). But these tumors are rarely cancerous, and rarely develop into full-blown cancer which is detectable anyway by other means, is uncommon, and treatable.
Stanley is not against screening. Mammograms and other screening modalities save lives (although he's quick to point out that diagnosing cancer early does not always lower the mortality rate-it depends on the type of cancer). But he and other radiologists are adamantly against asymptomatic people undergoing whole body scans as part of a health program.
Let's face it: blanketing yourself with radiation is not healthy. Because there is a risk involved, serious consideration should be given to whether the benefit is likely to be offset by the damage a CT scan does to the body. By all means, a person at risk for a disease, either because of lifestyle or genetics, should get whatever tests they need to assure them they are healthy. In most cases, tests not involving radiation can be done first. These tests should be exhausted before a CT is considered. If a CT scan is warranted, it should be done-correctly, with proper contrast material, by an experienced radiologist in that field. Contrast material increases the ability of the radiologist to detect small cancers, precancerous conditions, and distinguish between something important and something that isn't. If a body scan is chosen as the first-line diagnostic tool and it finds something, chances are the scan will have to be repeated with intravenous contrast material, subjecting the scanee to a double dose of radiation.
Many people who have undergone body scans did so because they weren't doing what they were supposed to do healthwise. The scan motivated them to pay attention to their health. And that would be fine if CT scans were totally benign. They're not, and any person contemplating a scan should ask themselves before they walk into a scan center if they really need a big dose of radiation to provoke them into doing what they already know they should be doing. Ask yourself: do I really need to undergo the equivalent of 1,000 x rays to find out I'm not exercising, I'm not eating right, and I need to buy a better mattress for my aching back? Can motivation and peace-of-mind be obtained another way?
CT scans have a place in diagnostics. To a person with symptoms of a serious disease or serious risk factors (such as smoking or familial heart disease), the benefit of getting a proper scan, with intravenous contrast, outweighs the risk. But the risk/benefit ratio collapses when the person getting a scan is a healthy individual with no symptoms; vague risk factors, and the scan is delivering a whopping dose of radiation. A person truly concerned about their health won't place that bet. We can't feel it, we don't see it, but we've got to believe that radiation is not healthy. We've got to listen to decades of data that tells us that radiation is something to be avoided when possible. Otherwise, we might as well sleep with Radium Ore Healing Pads tucked under our pillows, as the manufacturer of those devices once suggested.
For the European Commission guidelines on radiation imaging, go to http://europa.eu.int, choose "Commission" and search "Radiation Protection 118". For information on x ray/CT equivalency, see pg. 19.
The International Commission on Radiological Protection can be accessed at www.ICRP.org. See page 11 of "Diagnostic Reference Levels in Medical Imaging" for radiation levels of CT scans.
For the American College of Cardiology/American Heart Association's position paper on EBCT, see http://www.acc.org.
Dr. Stanley's comments will be published in an upcoming issue of the American Journal of Roentgenology.
For information on radiation, see http://www.x-raysandhealth.org.
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