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How to Know When You Need a 3D Mammogram

How to Know When You Need a 3D Mammogram

Digital breast tomosynthesis, a.k.a. 3D mammography, is being made available to more and more American women every day.

I recently booked an appointment for my first-ever mammogram. During the call, I was offered the option of having a three-dimensional (3D) mammogram, which, it turned out, my health insurance covered.

Apparently, I’m part of a trend. According to the U.S. Food and Drug Administration (FDA), 3,240 certified imaging centers had 3D mammogram technology as of April 1, 2017—about 37 percent of all certified facilities. By the same date in 2019? That number had leapt to 5,117 centers, or 59 percent.

Needless to say, 3D mammography—a.k.a. digital breast tomosynthesis (DBT)—is being made available to more American women every day. Although not yet recommended by the U.S. Preventive Services Task Force (USPSTF) over two-dimensional (2D) mammography, it’s approved by the FDA and increasingly covered by health insurance plans. Some influential medical organizations, like the National Comprehensive Cancer Network and the American College of Radiology, are throwing more support behind it, as well.

So, what is a 3D mammogram, exactly? What are the advantages and drawbacks relative to 2D mammograms? What should you expect if you have one, and most importantly—should you get it at all?

The basics of 3D mammograms
About 1 in 8 American women will develop breast cancer at some point. The earlier it’s discovered, the easier it is to treat, and the better your odds of survival. Mammograms are the best way to screen for breast cancer, as they can reveal growths in people who don’t yet have symptoms. During a typical 2D mammogram, X-ray images of your breasts are taken from a pair of angles—the top and the side.

Now, there’s mounting evidence that using 2D imaging together with 3D imaging could be even more effective for finding cancer. That’s because when you have a 3D mammogram, several pictures are taken from multiple angles. A computer then combines them into one three-dimensional composite image. This creates a more detailed representation of your breast and can help radiologists pick out abnormalities more easily.

“Think about a loaf of bread,” suggests Hildegard Toth, MD, a radiologist at NYU Langone Health in New York City. “Looking at the whole loaf at once, you don’t know what’s in the middle of it. If you slice it up, you can see each slice separately.”

While many imaging centers take 2D independently of 3D images, newer machines at some capture both types of images at the same time. The computer simply uses individual slices of the 3D mammogram to construct 2D images, Dr. Toth says.

The potential benefits of 3D mammograms
Though more studies are needed, there are multiple possible upsides to 3D mammography. One of the biggest is a reduction in the recall rate.

“Fewer women have to be called back for additional views,” Toth says. Estimates vary widely, but one large study published in June 2014 in JAMA found that consulting 3D and 2D mammograms together lowered recalls by about 16 percent.

This is partly because 3D mammograms provide better views in the first place, so abnormalities that are found might not need additional imaging. It’s also because 3D mammography may cut down on false positives, or suspicious findings that may initially look like cancer, but end up being relatively harmless. False positives can lead to extra stress and costly additional testing.

Another potential advantage of 3D mammography is the ability to detect more cancers; research generally suggests that combining it with 2D mammography is a slight improvement over using 2D by itself. This may be especially helpful for women with dense breasts, who have higher odds of developing breast cancer. A 2019 analysis published in JAMA Oncology indicated that adding 3D mammograms found 2.27 more cancers per 1,000 women with higher breast density, compared to consulting 2D images alone.

The potential drawbacks of 3D mammograms
The jury is still out, but there could be certain downsides to 3D mammography. First, when a 3D mammogram is done separately from a 2D mammogram, you may be exposed to a little more radiation. “However,” Toth says, “that dose is still way below the government limit.” In newer machines that perform both functions simultaneously, that exposure is diminished.

There’s also a potential for overdiagnosis, meaning a 3D mammogram could detect breast changes that might never evolve into clinically significant, potentially life-threatening cancer. These findings can result in unnecessary treatment, including biopsies, surgery, and radiation.

And although it’s not a drawback, per se, it’s worth noting that 3D mammograms are still relatively new. As such, there haven’t been long-term studies conclusively proving that they lower mortality rates or improve quality of life compared to 2D mammograms.

The Tomosynthesis Mammographic Imaging Screening Trial (TMIST), a clinical trial supported by the National Cancer Institute, is among those seeking to shed more light. Beginning in 2017, researchers set out to enroll and monitor 165,000 healthy women between the ages 45 of 74 who plan on receiving regular screening mammograms. When the trial ends in 2025, they’ll compare 2D to 3D mammogram results to see if the latter really is better at finding life-threatening cancer.

Moving forward
Given the potential risks and benefits of 3D mammograms, the decision to have one is ultimately up to you and your doctor. I went ahead and have no regrets.

Toth, who supports 3D mammograms “100 percent” says if you decide on a 3D screening, you should confirm that your health insurance will pay for it and whether you’ll need additional preauthorization. Though a few states now mandate coverage for 3D mammograms, most don’t, and some private plans don’t cover them yet. Medicare will pay for annual 3D mammograms when they’re done in conjunction with 2D mammograms.

Once you’ve checked your coverage, the process itself is much the same as getting a 2D mammogram. Be sure to pick an FDA-certified imaging facility and make an appointment for when your breasts are less likely to be tender. If you’re breastfeeding and it’s a routine screening (meaning there are no cancer symptoms present), you should postpone until a few months after weaning, Toth says.

Your mammogram should take under 20 minutes. It’s a relatively short time for a screening that may ultimately save your life. Time—and lots more research—will fill us in on the details.

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