Are Mammograms Safe?
Mammogram myths have become so common that people are skipping breast cancer screenings for fear of radiation. But the truth is that mammograms are safe, they're accurate, and they save lives. They can find breast cancer early, up to three years before you have any signs or symptoms — and earlier-stage breast cancers are easier to treat. The low levels of radiation from mammograms are not nearly as big a risk as the breast cancers that a mammogram can find.
Mammogram benefits
“Mammography is the mainstay of breast cancer screening. It has the best evidence behind its impact on breast cancer mortality,” says Kathryn Lowry, MD, an associate professor of radiology at the University of Washington School of Medicine and a physician at the Fred Hutch Cancer Center.
A large body of research shows that mammograms save lives and reduce the risk of advanced breast cancer:
A 27-year study of nearly 1.2 million women found that people who had a mammogram every other year were 30%–50% less likely to die from breast cancer than people who didn’t.
An analysis of four large studies found that mammograms reduce the risk of dying from breast cancer by 15% for women aged 40 to 74.
A study of nearly 500,000 women found that women who had mammograms were 41% less likely to die from breast cancer within 10 years and had a 25% lower risk of advanced breast cancer.
The combined results of six models suggest that annual mammograms from ages 40 to 84 reduce the risk of dying from breast cancer by 40%.
Although the benefits of mammograms far outweigh the risks, it’s important to understand these risks — and how small they are.
Do mammograms cause cancer?
Mammograms use low doses of radiation to create images of the breast, which radiologists then check for breast cancer. In high doses, radiation can increase cancer risk. But the dose of radiation received during a screening mammogram is very low.
As we move through our daily lives, we’re exposed to extremely small amounts of radiation from the soil, water, rocks, and air. The dose of radiation from a mammogram is equal to what you would be exposed to from your natural environment over about seven weeks, according to the American Cancer Society. A one way flight from Los Angeles to New York City has the same amount of radiation exposure as a mammogram. The cancer risks from this level of radiation are very low.
It’s hard to put into numbers what those risks are, exactly. Researchers use mathematical risk models to investigate this, but they may overestimate the radiation risk of mammograms. This is because they rely on evidence of people who have health complications after being exposed to much higher levels of radiation than they would get from a mammogram, Lowry says. And a high dose of radiation may be much more dangerous than a low dose.
Even with that potential overestimation, though, models show that the radiation risks of mammograms are small, especially when compared to the number of lives screening saves.
Models estimate that for every 100,000 women who get a mammogram annually from ages 40 to 74:
the radiation from the mammograms will cause 125 cases of breast cancer, leading to 16 deaths, but
the mammograms will save 968 lives through early diagnosis of breast cancer.
Another study looked at how long it would take one woman to get a breast cancer diagnosis from annual screening. It found that, for a woman getting annual mammograms from age 40 to 49, radiation would cause a fatal breast cancer diagnosis once every 76,000 to 97,000 years.
Here’s one last way to think about it: According to the annual screening model, the breast cancer mortality benefit-to-risk ratio of annual screening mammograms is 60:1. So mammograms are 60 times better for you than they are bad for you.
The radiation risks are greater for people who need to have more pictures taken during a mammogram, such as those with implants or large or dense breasts. But the overall risk is still low, models find, especially when compared to the number of lives saved by the early detection of breast cancer from mammograms.
Should you get a mammogram?
Yes, you should follow mammogram guidelines for your level of breast cancer risk. The benefits of mammograms far outweigh the risks. Statistically, you’re more likely to be harmed by breast cancer than by mammogram radiation.
Even for women who need more pictures during a mammogram, and thus more radiation, there’s no situation in which they should skip screening to avoid radiation, Lowry says.
“Unfortunately, in recent years mammograms have gotten a bit of a bad rep,” Lowry says. But while it’s true that a mammogram isn’t 100% safe,” she says, “it's still the most effective and most accessible breast cancer screening tool that we have.”