Can Mammogram Radiation Cause Breast Cancer?

Can Mammogram Radiation Cause Breast Cancer?
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What is the risk-benefit ratio of the cancers picked up by mammograms and the cancers caused by mammograms?

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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.

Over the last few decades, our radiation exposure has nearly doubled, thanks almost exclusively to medical sources, such as CT scans. We’ve known that higher-dose radiation, like CT scans and angiograms, can cause breaks in our DNA, but now we know that mammograms can, too. You can find X-ray induced DNA damage in white blood cells drawn from women right after her mammogram.

That’s amazing they can find evidence of DNA breaks; I mean, how much blood is there in the breast in the first place? And then you squeeze it out during the procedure, and then it mixes with the unexposed blood from the rest of the body, and you can still pick up the DNA damage circulating throughout her system. So, what they found “underestimate[s]” the DNA damage in the breast tissue itself.

But, doctors tell women, “There is nothing to worry about.” Just a few extra cases of breast cancer are caused by mammograms. Wait; what? Mammograms causing breast cancer? Yes. The “risk of radiation-induced breast cancer” from modern, low-dose digital mammograms depends on how often you get screened, and at what age you start. “For a [group] of 100 000 women…screened annually from age 40 to 55 years and [every other year until] age 74…, it is predicted that there will be 86 cancers induced and 11 deaths due to radiation-induced breast cancer.” Meaning they estimate 11 of those women will die from breast cancer that they would never have gotten if they decided not to get mammograms—not expose themselves to that radiation. They even calculated the lifetime risk of developing a radiation-induced breast cancer after just getting a single mammogram.

Women with large breasts may carry additional risk, because their mammograms may require additional views, and the greater radiation dose is expected to translate into “a greater risk for radiation-induced breast cancer and breast cancer death”—as much as triple the lifetime attributable risk of developing breast cancer because of the mammogram radiation exposure.

The earlier one starts screening, the higher the risk as well, since there’s more time for a cancer to grow. This comes up for women with BRCA gene mutations, for whom screening is sometimes recommended starting in their twenties. But, at that age, mammograms may cause as many breast cancer deaths as they prevent. A net benefit would be expected at 35 years old, though, and likely the same for women without BRCA mutations. Yes, “The risk of radiation-induced cancer from mammography is not negligible, [but] the potential for mortality benefit is generally considered to outweigh the risk of death from radiation-induced [breast cancer] attributed to mammography screening”—”a benefit-to-risk ratio in lives of” 10 to one or more.

Now, these estimates on how much breast cancer mammogram X-rays may cause relies “heavily on data from the atomic bomb survivors,” who were exposed more to gamma rays, which are like high-energy X-rays. But, it turns out the lower energy X-rays used in mammography are even worse—”approximately four times…more effective in causing mutational damage than higher energy X-rays.” And, “[s]ince current radiation risk estimates are based on the effects of…gamma [rays], this implies that the risks of radiation-induced breast cancers [from] mammography X-rays” is four times worse than previously estimated. But, even if that were true, the benefit-to-risk ratio would still favor mammograms—which is why you see editorials in radiology journals like this: “concern about radiation exposure should not prevent [a woman] from undergoing life-saving mammography screening.”

But: “No trial has ever shown an overall mortality benefit from screening mammography. Thus, if there is a detrimental effect of radiation exposure from mammography, even a small effect could offset [the benefits].”

Please consider volunteering to help out on the site.

Image credit: AlarconBenthos via pixabay. Image has been modified.

Motion graphics by Avocado Video

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.

Over the last few decades, our radiation exposure has nearly doubled, thanks almost exclusively to medical sources, such as CT scans. We’ve known that higher-dose radiation, like CT scans and angiograms, can cause breaks in our DNA, but now we know that mammograms can, too. You can find X-ray induced DNA damage in white blood cells drawn from women right after her mammogram.

That’s amazing they can find evidence of DNA breaks; I mean, how much blood is there in the breast in the first place? And then you squeeze it out during the procedure, and then it mixes with the unexposed blood from the rest of the body, and you can still pick up the DNA damage circulating throughout her system. So, what they found “underestimate[s]” the DNA damage in the breast tissue itself.

But, doctors tell women, “There is nothing to worry about.” Just a few extra cases of breast cancer are caused by mammograms. Wait; what? Mammograms causing breast cancer? Yes. The “risk of radiation-induced breast cancer” from modern, low-dose digital mammograms depends on how often you get screened, and at what age you start. “For a [group] of 100 000 women…screened annually from age 40 to 55 years and [every other year until] age 74…, it is predicted that there will be 86 cancers induced and 11 deaths due to radiation-induced breast cancer.” Meaning they estimate 11 of those women will die from breast cancer that they would never have gotten if they decided not to get mammograms—not expose themselves to that radiation. They even calculated the lifetime risk of developing a radiation-induced breast cancer after just getting a single mammogram.

Women with large breasts may carry additional risk, because their mammograms may require additional views, and the greater radiation dose is expected to translate into “a greater risk for radiation-induced breast cancer and breast cancer death”—as much as triple the lifetime attributable risk of developing breast cancer because of the mammogram radiation exposure.

The earlier one starts screening, the higher the risk as well, since there’s more time for a cancer to grow. This comes up for women with BRCA gene mutations, for whom screening is sometimes recommended starting in their twenties. But, at that age, mammograms may cause as many breast cancer deaths as they prevent. A net benefit would be expected at 35 years old, though, and likely the same for women without BRCA mutations. Yes, “The risk of radiation-induced cancer from mammography is not negligible, [but] the potential for mortality benefit is generally considered to outweigh the risk of death from radiation-induced [breast cancer] attributed to mammography screening”—”a benefit-to-risk ratio in lives of” 10 to one or more.

Now, these estimates on how much breast cancer mammogram X-rays may cause relies “heavily on data from the atomic bomb survivors,” who were exposed more to gamma rays, which are like high-energy X-rays. But, it turns out the lower energy X-rays used in mammography are even worse—”approximately four times…more effective in causing mutational damage than higher energy X-rays.” And, “[s]ince current radiation risk estimates are based on the effects of…gamma [rays], this implies that the risks of radiation-induced breast cancers [from] mammography X-rays” is four times worse than previously estimated. But, even if that were true, the benefit-to-risk ratio would still favor mammograms—which is why you see editorials in radiology journals like this: “concern about radiation exposure should not prevent [a woman] from undergoing life-saving mammography screening.”

But: “No trial has ever shown an overall mortality benefit from screening mammography. Thus, if there is a detrimental effect of radiation exposure from mammography, even a small effect could offset [the benefits].”

Please consider volunteering to help out on the site.

Image credit: AlarconBenthos via pixabay. Image has been modified.

Motion graphics by Avocado Video

Doctor's Note

For more on radiation exposure from other sources, see:

What about cell phones? See:

We’re halfway through my 14-part series on mammograms. If you missed any previous videos, check out:

The greatest radiation risk from mammograms is the exposure to radiation treatments for overdiagnosed pseudodisease. I explore that more in my next video. See that and the rest of my series:

If you want to watch the entire series right now, you can stream it for a donation to NutritionFacts.org by going here.

For more on breast cancer, see my videos Oxidized Cholesterol 27HC May Explain Three Breast Cancer Mysteriesand Eggs and Breast Cancer.

I was able to cover colon cancer screening in just one video. If you missed it, check out Should We All Get Colonoscopies Starting at Age 50?.

Also on the topic of medical screenings, see Is It Worth Getting Annual Health Check-Ups? and Is It Worth Getting an Annual Physical Exam?.

If you haven’t yet, you can subscribe to my videos for free by clicking here.

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