Cancer Risk from CT Scan Radiation

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Pediatric CAT scans are estimated to cause hundreds of cancer deaths every year.

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Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

The greatest radiation exposure risk comes not from Fukushima fallout, or the polonium naturally found in seafood, but from doctors. This was the study that really shook things up. “Estimated Risks of Radiation-Induced Fatal Cancer from Pediatric [CAT scans],” which concluded that the best available risk estimates suggest that pediatric CT scans will result in significantly increased lifetime cancer risk.

How increased? Well, in the United States, of the approximately 600,000 abdominal and head CT scans annually performed in children under the age of 15, 500 of these individuals might ultimately not just get cancer, but die from cancer attributable to that CAT scan radiation. In response to this revelation, the editor-in-chief of the leading radiology journal admitted that radiologists have not been “watching out for children.”

These estimates were based on data from Japanese atomic bomb survivors, in terms of how many cancer deaths one can expect from what kind of radiation dose. But, there’s never been a study actually documenting the excess cancers—until now.

Turns out the X-rays released by CAT scanners might be twice as carcinogenic as the higher energy gamma rays released from the atomic bombs. A few CT scans may triple the risk of brain tumors and leukemia in children. Other studies are being performed around the world to quantify the risk, and should be out in the next few years.

Until then, what can we do? Well, first of all, we should only get X-rays when absolutely necessary. Good evidence suggests that between a fifth and a half of CAT scans aren’t necessary at all; they could be replaced with another type of imaging, or just not done—period. That’s a lot of added cancer risk, for no added benefit.

Now, this kind of CAT scan is okay, but this kind carries risks. The risk of developing cancer after a single CT scan may be as high as one in a hundred for a baby girl. It can take years for cancer to develop, so that’s why the risk is lower in the elderly, since they have fewer years to live. The diagnostic medical radiation dealt out in one year is estimated to cause 2,800 breast cancers among women in the United States, and 25,000 or so other cancers. That’s doctors causing cancer.

One chest CT scan is like getting four hundred chest X-rays, and a stress test heart scan can be like getting over a thousand X-rays. Doctors need to communicate the risks of these procedures. For example, the risk of a chest CT is like the risk of having a car crash during 2,500 miles of highway driving, or of smoking 700 cigarettes. You pick up a pack of cigarettes, and there’s a warning label. But then, you go in for a thallium heart scan, and no one minds telling you that the risk corresponds to smoking 1,400 cigarettes. One in every 270 middle-aged women that gets an angiogram may get cancer because of that one test.

The best way to avoid the risks of radiation scans is the same way to best avoid the risks of medication—living and eating healthy enough to help avoid the need for them in the first place.

Please consider volunteering to help out on the site.

Images thanks to Tabbymom Jen via flickr and Jacopo Werther via Wikimedia

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

The greatest radiation exposure risk comes not from Fukushima fallout, or the polonium naturally found in seafood, but from doctors. This was the study that really shook things up. “Estimated Risks of Radiation-Induced Fatal Cancer from Pediatric [CAT scans],” which concluded that the best available risk estimates suggest that pediatric CT scans will result in significantly increased lifetime cancer risk.

How increased? Well, in the United States, of the approximately 600,000 abdominal and head CT scans annually performed in children under the age of 15, 500 of these individuals might ultimately not just get cancer, but die from cancer attributable to that CAT scan radiation. In response to this revelation, the editor-in-chief of the leading radiology journal admitted that radiologists have not been “watching out for children.”

These estimates were based on data from Japanese atomic bomb survivors, in terms of how many cancer deaths one can expect from what kind of radiation dose. But, there’s never been a study actually documenting the excess cancers—until now.

Turns out the X-rays released by CAT scanners might be twice as carcinogenic as the higher energy gamma rays released from the atomic bombs. A few CT scans may triple the risk of brain tumors and leukemia in children. Other studies are being performed around the world to quantify the risk, and should be out in the next few years.

Until then, what can we do? Well, first of all, we should only get X-rays when absolutely necessary. Good evidence suggests that between a fifth and a half of CAT scans aren’t necessary at all; they could be replaced with another type of imaging, or just not done—period. That’s a lot of added cancer risk, for no added benefit.

Now, this kind of CAT scan is okay, but this kind carries risks. The risk of developing cancer after a single CT scan may be as high as one in a hundred for a baby girl. It can take years for cancer to develop, so that’s why the risk is lower in the elderly, since they have fewer years to live. The diagnostic medical radiation dealt out in one year is estimated to cause 2,800 breast cancers among women in the United States, and 25,000 or so other cancers. That’s doctors causing cancer.

One chest CT scan is like getting four hundred chest X-rays, and a stress test heart scan can be like getting over a thousand X-rays. Doctors need to communicate the risks of these procedures. For example, the risk of a chest CT is like the risk of having a car crash during 2,500 miles of highway driving, or of smoking 700 cigarettes. You pick up a pack of cigarettes, and there’s a warning label. But then, you go in for a thallium heart scan, and no one minds telling you that the risk corresponds to smoking 1,400 cigarettes. One in every 270 middle-aged women that gets an angiogram may get cancer because of that one test.

The best way to avoid the risks of radiation scans is the same way to best avoid the risks of medication—living and eating healthy enough to help avoid the need for them in the first place.

Please consider volunteering to help out on the site.

Images thanks to Tabbymom Jen via flickr and Jacopo Werther via Wikimedia

Doctor's Note

As I explain in my full-length live presentation on preventing, arresting, and reversing the 15 top killers (see Uprooting the Leading Causes of Death), adverse drug reactions from prescription medications are estimated to cause more than 100,000 deaths in the United States every year, making doctors the sixth leading cause of death. That’s not counting other “iatrogenic” (physician-caused) harm—such as medication errors, or infections acquired in hospitals. My profession needs to do a better job of offering fully informed consent, clearly and comprehensively explaining the risks and benefits of each alternate course of action.

The risk associated with the thallium heart scans was shocking to me. By eating healthy, we may not only eliminate the death and disability associated with heart disease, and its treatment (such as open heart surgery), but also the risks associated with heart disease diagnosis. See:

What was that about radioactive polonium in seafood? See Fukushima & Radioactivity in Seafood.

And what about getting X-rays at the dentist? See Do Dental X-Rays Cause Brain Tumors?

For further context, check out my associated blog posts: How Risky Are CT Scans?; Are Dental X-Rays Safe?; Dealing with Air Travel Radiation Exposure; and Ginger & Lemon Balm for Radiation Exposure.

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