A medical provider views the result of a breast cancer screening test.

The next time you go for a routine breast cancer screening, you may find that your clinic offers you a range of options, including the standard mammogram, a 3D mammogram, an ultrasound, or even a breast MRI.

Which breast cancer screening is best for you?

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That's a challenging question to answer. Due to conflicting recommendations from different medical organizations, it’s complicated enough knowing when and how often to get breast cancer screening. (For help, see our report on when to get a mammogram.)

Now, say some experts, the growing number of ways you can be screened can make the breast screening process even more confusing. “It’s really difficult to navigate and feel like, ‘I know the right answer for me,’” says Tracy Onega, Ph.D., associate professor in the department of biomedical data science and of epidemiology and the Dartmouth Institute for Health Policy and Clinical Practice.

To help you figure out what’s best for you, CR looked at the research and talked with experts in breast cancer screening about the pros and cons of the tests you may be offered.

Standard Mammography

This is a low-dose x-ray used to detect abnormalities in the breast that could indicate cancer. Today, most mammograms are performed digitally, rather than using film images.

How well does it work? Not all medical experts agree on how effective mammography is at finding cancer. At its best, mammography can reveal potentially dangerous tumors before you experience symptoms, when they’re small and presumably much easier to treat.

In some instances, however, the test can result in false positives (false alarms) that require follow-up tests, or it might find small tumors in the breast that get treated with surgery or radiation even though they're unlikely to ever be harmful.  

The U.S. Preventive Services Task Force (USPSTF), an independent panel of medical experts that evaluates preventive medical services, estimates that as many as 1 in 8 cancers diagnosed through mammography would never have caused any harm, though other interpretations of existing data put the estimate lower.

Is this screening test right for you? For women at normal risk, most experts say yes, but differ on when and how often. The USPSTF, the American Cancer Society (ACS), and American College of Obstetricians and Gynecologists (ACOG) recommend that women begin regular mammography screening at least by age 50, but can choose to start as early as age 40.

The Task Force recommends standard mammograms every two years, while ACS says that women should receive them yearly between ages 45 and 55, and every other year after age 55. ACOG says women should have the choice to screen every year or every other year.

Note that a 2017 study published in the journal Cancer found that screening annually, starting at age 40 led to more cancers being detected, but also led to more women receiving false positive results. When deciding at what age to start and how often to get a mammogram, consider your willingness to put up with the possibility of a false positive or overtreatment, and your personal risk factors—which may change over time, Onega says.

3D Mammography

Like standard digital mammography, 3D mammography, or digital breast tomosynthesis, is an x-ray test. But instead of taking flat images of the breast, it takes many pictures of the breast from different angles. This gives radiologists a three-dimensional picture of the breast, and, in theory, a more accurate picture.

How well does it work? Some studies suggest that 3D mammography finds more cancers than the standard test. But the USPSTF says there's insufficient evidence to recommend 3D mammography as the primary breast cancer screening tool, mainly because there haven’t yet been studies on whether it reduces breast cancer deaths.

“It is great to find more cancers, but we want to see if the new technology improves on our ability to find more of the aggressive cancers early,” says Robert A. Smith, Ph.D., vice president of screening with the American Cancer Society. What we need is additional evidence on, “how much of an overall advantage 3D offers compared with conventional mammography,” he adds.

One pro is that 3D mammography may reduce the need for followup mammograms. Two analyses published in 2016 found that 3D mammography plus standard digital mammography cut  the number of women who had to return for more tests. “We feel it’s a better mammogram because it has the ability to detect more cancers while calling back fewer women for more testing,” says Sally Herschorn, M.D., division chief and medical director of breast imaging at the University of Vermont Medical Center in Burlington.

Is this screening test right for you? Maybe. If your insurance covers 3D mammography it likely has some advantages over standard mammography.

But until scientists determine how significant those advantages are, “If the facility you use for screening does not have 3D yet but is a high-quality screening center that also has all your prior images stored for comparison, you can feel confident that you will still receive a good screening test,” Smith says. For advice on how to find a good screening location, see our report on where to get a mammogram.

And if you’re concerned about radiation exposure, note that depending on the type of 3D technology used, this test may deliver a higher dose of radiation than standard mammography alone.

Ultrasound

In ultrasound, sound waves are used to produce images of the inside of the breast—and detect any masses there. During this painless test, a technician passes a scanning wand over the breast area or a machine scans most of the breast.

Ultrasound is often done as a follow-up test, giving doctors a better look at a suspicious abnormality found on a mammogram. But some facilities also offer it as a first screening test in addition to routine mammography.

How well does it work? According to Herschorn, ultrasound may detect more cancers than standard mammography, but the false alarm rate is also probably higher. “This is because there are many abnormalities in the breast that are not cancer and can be seen with ultrasound,” Herschorn says.

Is this screening test right for you? If you have dense breasts—a lot of fibrous tissue in the breast that can make cancers harder to see on a mammogram—maybe.

Having dense breasts does raise your risk of breast cancer, but only by a few percentage points. And it’s only one possible factor out of more than a dozen, including a family or personal history of breast cancer. So even if your breasts are dense, your overall risk may be low. (According to the nonprofit group Are You Dense, more than 30 states now require radiologists to inform women of their breast density status.)

Some research, such as a 2015 study in Annals of Internal Medicine, suggests that adding ultrasound screening to mammography may be most beneficial for women who are already at high risk of breast cancer within five years.

Talk to your doctor about your risk for breast cancer, and whether you might benefit from ultrasound. You can also try using a risk calculator like the one offered by the National Cancer Institute.

Getting an ultrasound along with a mammogram may be a good alternative for women whose breast cancer risk level is high enough that they would qualify for MRI screening (see below), but who are claustrophobic and can’t tolerate an MRI, Smith says.

MRI

Magnetic resonance imaging, or MRI, uses strong magnets and radio waves to create a detailed image of the breast. Often, a dye is injected into your breasts to enhance the image.

How well does it work? While screening with MRI may be more likely to cause a false alarm than a standard mammogram, evidence also suggests that MRI may detect substantially more cancers than mammograms or ultrasound.

MRI may also be better at picking up cancers that are more likely to be aggressive, says Smith. That's because the test can reveal how active a tumor is and the extent of its spread inside the breast— and the existence of other, smaller tumors that mammography may not have detected.

Is this screening test right for you? Breast cancer screening with MRI is usually only indicated in conjunction with mammogram for women with a very high lifetime risk of breast cancer—at least 20 percent. You may be in this category if you carry a genetic mutation (especially BRCA1 or BRCA2) that predisposes you to cancer; have a parent, sibling, or child with such a mutation; have a strong family history of breast cancer; or received radiation therapy to the chest between ages 10 and 30.

If you’re unsure, you doctor can help you figure out whether your personal level of risk reaches the threshold for screening with MRI.

The test can be very expensive, but according to the ACS, most private insurance plans cover the test for those at high risk.

Other Screening Options

You may have heard of—or even been offered—still other newer screening tests, such as molecular breast imaging, or optical imaging tests.

But it may be best to skip these for the moment. “Women should know if they’re offered one of these that we know very little [about them],” says Dartmouth Institute's Onega. “They’re untested in general populations.” They're also unlikely to be covered by insurance.

Editor's note: This piece incorrectly referred to the U.S. Preventive Services Task Force as a "government group." The task force is an independent panel of medical experts. The story has been updated.