False-positive mammograms discourage women from breast cancer screening, study finds. Why it happens — and what to do.

Every year, millions of women get mammograms to screen for breast cancer. About 10% of them are called back for further testing. And 7% to 12% of those women receive a false-positive result, meaning that the mammogram detects something that looks like cancer, but turns out not to be. It's not hard to imagine the emotional rollercoaster that could put you on. Many women are not eager to repeat the experience, and those who receive a false-positive cancer detection are far less likely to return for their next screening, according to new research published in the Annals of Internal Medicine.

While experts are sympathetic to the stress false positives can cause, they're urging women to keep going to annual screenings, and sharing tips to help ease people’s minds. Here's what to know.

What did the study find?

The study looked at data on more than a million patients between ages 40 and 73. The researchers found that, after getting a negative mammogram result, 77% of all women came back for their next scheduled screening. But for women told to come back for another mammogram in six months due to a false positive, only 61% of them returned. The study also found that 67% of women came back for another screening when a biopsy was recommended. The return rate dropped even lower when women received two false-positives in a row; just 56% came to their next mammograms.

What is a false-positive mammogram?

Mammograms are X-rays of breast tissue. They are essential tools for cancer screening but, on their own, they are not able show definitively whether or not there is cancer in a breast. Instead, a radiologist can typically differentiate between normal and abnormal breast tissue, indicating changes that may include developing cancer.

"Some women have what we call more 'busy' breasts, where they have more things that, based on mammography alone, make it harder for a screening radiologist to say, 'This is all clear,'" Dr. Lynn Dengel, assistant professor of surgical oncology at the University of Virginia, tells Yahoo Life. Dense breast tissue — which is more common among younger women, especially those who have low BMIs, and Black women — can make it more difficult to distinguish if cancer is visible on a mammogram. According to Dengel (and the American Cancer Society), cysts, previous procedures (including breast biopsies) and benign tumors are all factors in making breast tissue difficult to decipher.

Radiologists look for calcifications, masses (cysts also look like masses on mammograms, though they're not cancerous), asymmetries, distorted shapes or patterns in breast tissue, and breast density. None of these showing up on your mammogram automatically means you have cancer. But they can result in a mammogram that's "positive" for an abnormality that looks like cancer, which may mean you need additional screening. "The vast majority of these [abnormalities] turn out not to be cancer," Dengel says.

That’s the good news. But the initial false-positive result can dissuade women from continuing to get screened, study co-author Diana Miglioretti, a University of California, Davis, professor of biostatistics, tells Yahoo Life. “False-positive results can lead to psychological stress, fear of having cancer, anxiety while waiting for results and the inconvenience and financial costs of returning for multiple visits, which can feel like a waste of time if the outcome is ultimately normal,” she explains.

How common is a false-positive mammogram, and why does it happen?

If someone gets a mammogram every year (as recommended) for 10 years, there is a 50% chance that they’ll get a false-positive at some point, according to the Susan G. Komen Foundation. False positives are very common. But fewer than one in 10 women who are called back for further testing are diagnosed with cancer as a result, according to the ACS. “It doesn’t mean you’re going to have a cancer just because you got called back” for more tests, Dengel stresses.

False positives are the trade-off of aggressive preventative screening. “We want to detect cancer as early as possible, so we try to find smaller- and earlier-stage cancers,” Dengel explains. “The upside is we’re doing a better job of detecting cancer earlier. The downside is that we're often finding things that don’t actually turn out to be cancer.”

State-of-the-art technologies are also helping reduce the odds of a false-positive mammogram. “For example, the shift to full-field digital mammography has led to lower recall rates, and this trend continues with newer technologies like tomosynthesis [3D imaging] compared to traditional 2D imaging,” Dr. Bhavika Patel, a breast imaging radiologist at Mayo Clinic, tells Yahoo Life.

What to do if you get a false-positive mammogram

First and foremost, “do the right thing and get your screenings,” including any follow-up tests you’re called back for after a mammogram, says Dengel.

Second, remember that knowledge is power, even when it’s anxiety-inducing. “While false positives can be stressful, they are often part of the process of catching cancer early when it is most treatable,” Patel says. “Knowing that the chance of a false positive is higher at your initial screening can help set expectations and reduce anxiety. Over time, as you have more comparison images from past mammograms, the likelihood of false positives typically decreases,” she explains.

You can also work with your doctor to come up with a personalized plan that fits your needs and budget. Both Dengel and Patel suggest calling your screening center to find out what types of mammography are available (keeping in mind that 3D will likely have a lower chance of false spositives) and what they might cost. You might also be able to cut out some of the anxious wait-time for results, says Miglioretti. Concerned women can ask their providers “if they can have their screening mammogram read while they wait and receive any necessary diagnostic work-up during the same visit,” she suggests.

Nobody wants to go through these processes, Dengel says, but “it’s an important part of screening and early detection, and those really are the best tools we have in terms of treating cancer.”