When should you get screened for breast cancer—and how often?

Earlier this year, the U.S. Preventive Services Task Force suggested several changes to its recommendations about when and how frequently women should begin receiving regular mammograms to screen for breast cancer. The updates were suggested after careful review of the latest evidence, according to John Wong, member of the USPSTF and internal medicine physician at Tufts University.

“Mammograms don’t prevent breast cancer from developing, they detect it at an earlier time,” Wong says. “In this draft recommendation, we're saying that all women should start getting screened every other year at age 40.”

It’s a change from previous guidelines that encourage annual screening beginning at age 50—and a particularly notable one especially as nearly 1 in 10 cases of breast cancer now occur in women under 45. However, while many in the field applaud the shift, they’ve also raised concerns that biannual mammograms could leave cancers undetected—and untreated—for too long.

“The survival benefits are the best when mammography is done yearly, starting at age 40,” says Priti Shah, director of Breast Imaging at VCU Health in Richmond, Virginia.

The recommendations are still in draft form. Here’s how to make sense of it all—and what to know about newer technologies coming down the pipeline that have the potential to help women test more frequently and catch cancer earlier, when it’s more treatable.

Why the recommendations are changing

Decades of extensive research have shown that breast cancer arises from a combination of genetic and environmental causes—from mutations in the BRCA1 and BRCA2 genes to risks such as alcohol consumption, physical inactivity, hormone therapy, and exposure to ionizing radiation (which can cause mutations in DNA).

(Should you get tested for a BRCA gene mutation? It’s complicated.)

Regardless of the cause, scientists have been using x-rays to identify breast cancer for over a century. The late 20^th century saw improved techniques, such as compressing breast tissue between plates to enhance image quality and newer strategies to develop images on film. Large-scale mammography trials in the 1980s and 1990s led to some of the first recommendations that women aged 40 and over should receive regular mammograms.

Over the years, however, that number was raised to 50, with the USPSTF telling women between 40 and 50 to get screened if they thought they would benefit. Some of this reasoning, Wong says, was due to increased awareness about mammography’s potential risks.

Mammography still relies on x-rays, which expose you to a small amount of radiation. It wasn’t entirely clear whether the potential harms from the radiation outweighed the benefits of a mammogram. There were other concerns, too. Like everything in medicine, the technique isn’t 100 percent effective at identifying cancer. Many of the concerning spots flagged by a radiologist reading a mammogram turn out to be something other than a malignancy. These false positives cost time and money, create anxiety, and potentially expose people to risks from other types of procedures such as biopsy.

One of the tasks of the USPSTF, Shah says, is trying to balance these risks and benefits.

“We need to address these risks, but we don’t want to throw the baby out with the bathwater,” she says.

(Our bodies are unique. Our cancers are too.)

And these risks and benefits aren’t static. They may shift throughout a person’s life as their health conditions and values change over time, and as medical science learns more about breast cancer risks and the potential benefits of mammography.

One of the biggest changes in recent years has been a rise in the number of women under 45 diagnosed with breast cancer. The U.S. Centers for Disease Control and Prevention estimates that 9 percent of all new cases of breast cancer are diagnosed in women younger than 45.

Although the USPSTF continued to encourage regular mammograms beginning at age 40, many of these women fell outside of its formal recommendations. This meant that they would only receive a diagnosis when they noticed changes to their breasts, such as lumps, thickening or swelling, and nipple discharge that isn’t breast milk.

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When the USPSTF team reviewed the new data, Wong says, they returned the starting age for mammography back to 40.

But are we screening enough?

However, instead of yearly mammograms, the task force changed the guidelines to every other year. The change sparked concern and criticism from some in the field.

“Overwhelming data shows that most lives are saved by annual screening starting at age 40,” says Aviva O’Connell, a breast imaging specialist at the University of Rochester Medical Center in New York. “If we delay screening until age 50 and only screen every two years, as many as 100,000 women will die.

(Breast cancer spreads more aggressively during sleep.)

Shah agrees. “We want to start screening younger because these cancers are more aggressive. We don’t want to wait two years.”

Other physicians have concerns about what it means for insurance coverage and health equity. Under the Affordable Care Act, all health insurance companies must cover 100 percent of the cost of recommended screening mammograms. While some insurance plans may retain full coverage for annual mammograms once women turn 40, others may change to biannual coverage since that will still comply with the law.

Given that Black and BIPOC women are significantly more likely to develop breast cancer, be diagnosed at a later stage, and die as a result of their disease, this lack of coverage will create a major health equity issue, says Toma Samantha Omofoye, a breast radiologist at the University of Texas MD Anderson Cancer Center.

“Disparities in cancer outcomes are due to issues across the healthcare spectrum. This makes access to early and frequent screening mammography an important part of addressing health disparities,” she says.

Is the future of breast cancer screening wearable?

For some people, however, even annual screenings may not be enough.

Widespread mammography has also raised awareness of the challenges of having dense breasts. Women with dense breasts—typically younger women—have more of the fibrous and connective tissue that provide structural support to the breast. This tissue is denser than fat and glands and appears solid white on mammograms.

Dense breasts, in and of themselves, aren’t a problem, Shah says. But they do make it more challenging to identify potential tumors on a mammogram. It’s why physicians have begun encouraging women with dense breasts to receive additional imaging with MRI and ultrasound in addition to their annual mammograms.

To help ease this screening burden, scientists are working to develop new and more accessible breast cancer screening technologies.

One such scientist is Canan Dagdeviren, an engineer in MIT’s Media Lab, who is building a wearable ultrasound machine that women can use with their everyday bra. She sketched out her prototype at the bedside of her dying aunt, whose breast cancer first appeared between biannual mammograms. By the time Dagdeviren’s aunt detected any changes, her cancer was too advanced to treat.

She sees her device as something women could use monthly, weekly, even daily, as part of their normal routines, as the ultrasound only takes a minute or two.

“Early detection is the key for survival. Our humble calculation shows that this technology has the potential to save 12 million lives per year globally,” she says.

And she doesn’t want to stop at breast cancer. Other types of tumors, such as prostate cancer, may also be detectable with wearable ultrasound.

But even as researchers like Dagdeviren continue to develop the screening tools of the future, O’Connell says that simply knowing your own body and paying attention to changes remains one of the most important strategies in detecting cancer.

“Just be aware of what's normal for you and then you can tell if something changes,” she says.