 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 break. 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 underestimates the DNA damage in the breast tissue itself. But doctors tell women there's 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's 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 doses 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 is well, since there's more time for a cancer to grow. This comes up for women with broccoli gene mutations for whom screening is sometimes recommended starting in their 20s, 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 broccoli 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 for radiation-induced breast cancer attributed to mammography screening, a benefit-to-risk ratio in lives of 10 to 1 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 are 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 since current radiation risk estimates are based on the effects of gamma rays, this implies that the risks of radiation-induced breast cancers for 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, concerned 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's a detrimental effect of radiation exposure from mammography, even a small effect could offset the benefits.