In 2023, the U.S. Preventive Services Task Force (USPSTF) proposed changes to its guidelines for breast cancer screening mammograms. These guidelines were finalized in April 2024. According to John Wong, a member of the USPSTF and an internal medicine physician at Tufts University, the updates followed a detailed review of the latest available data. "Mammograms do not prevent breast cancer from developing, but they detect it at an earlier stage," explains Dr. Wong. "In this draft of recommendations, we explain that women should begin screening every two years starting at age 40." In France and other European countries, organized screening typically targets women aged 50 to 74, with mammograms every two years for those with an average risk. However, discussions about lowering the starting age continue, given the rise in diagnoses among younger women. These new American recommendations represent a notable shift, as nearly one in ten breast cancer cases today occurs in women under 45 years of age. While many specialists welcome these changes, others are concerned that reducing the frequency of mammograms from once a year to once every two years might delay detection and treatment. "Women have a greater chance of surviving breast cancer when they have a mammogram every year, starting at age 40," says Priti Shah, director of the breast imaging service at VCU Health Hospital in Richmond, Virginia. The recommendations are still under deliberation. Here is how to navigate them and what to know about the new technologies that may help women have more frequent exams and detect cancer earlier, when it is easier to treat. Decades of research have shown that breast cancer results from a combination of genetic and environmental causes, such as mutations in the BRCA1 and BRCA2 genes, and other risks such as alcohol consumption, lack of physical activity, hormone therapy, and exposure to ionizing radiation. Scientists have used X-rays to detect breast cancer for more than a century. By the end of the 20th century, several techniques were improved, including compressing breast tissue between plates to increase image quality and new strategies for printing medical images on film. Large-scale screening trials in the 1980s and 1990s led to the first recommendations for regular mammograms for women aged 40 and older. Over the years, however, the age for screening was raised to 50 in the U.S., as the USPSTF recommended that women aged 40 to 50 should be screened if they deemed it necessary. In France, the National Cancer Institute (INCa) estimates that 80% of breast cancers occur after the age of 50, which is why it recommends regular screening for women aged 50 and older. According to Wong, this change in recommendations is partly explained by an increased awareness of the risks associated with mammography. Mammography still relies on X-rays, which expose patients to a small amount of radiation. However, it is unknown whether the potential disadvantages of radiation outweigh the benefits of a mammogram. In addition, this technique is not 100% effective in identifying cancer. Many suspicious abnormalities detected during a mammogram ultimately do not correspond to cancer. Radiologists determine that they are something other than malignant tumors. These false positives cost time and money, create anxiety, and potentially expose those concerned to risks associated with other procedures such as biopsies. According to Shah, one of the tasks of the USPSTF is to try to find a balance between these risks and benefits. "We must take these risks into account, without throwing the baby out with the bathwater," she says. Especially since this risk-benefit balance is not fixed. It can change throughout life, depending on our health status and as medical science learns more about breast cancer risks and the potential benefits of mammography. One of the most significant changes in recent years has been the increase in the number of women under 45 years of age diagnosed with breast cancer. The U.S. Centers for Disease Control and Prevention estimate that 9% of all new breast cancer cases are diagnosed in women under 45 years of age. Although the USPSTF has continued to encourage regular mammograms starting at age 40, many of these women were not covered by its formal recommendations. This meant that they would only receive a diagnosis when they noticed abnormalities in their breasts, such as lumps, thickening or swelling, and nipple discharge other than breast milk. When the USPSTF team examined the new data, Wong explains, it lowered the age of first mammograms to 40 years. However, instead of proposing annual mammograms, the task force changed their frequency to once every two years. This change has raised concerns and criticism from some specialists. "Overwhelming data show that most lives are saved through annual screening starting at age 40," explains Aviva O’Connell, a breast imaging specialist at the Rochester Medical Center in the state of New York. "If women are only screened every two years by the end of their 40s, no less than 100,000 women will die from breast cancer." Dr. Shah agrees with this view. "We want to start screening earlier because these cancers are more aggressive. We don't want to wait two years." Other doctors are concerned about the impact on insurance coverage and health equity. Under the U.S. Affordable Care Act, all health insurance companies must cover 100% of the cost of recommended screening mammograms. While some insurance plans may maintain full coverage of annual mammograms once women reach 40 years of age, others may switch to biennial coverage, as this is still in compliance with the law. Given that women of color are much more likely to develop breast cancer, be diagnosed at a more advanced stage, and die from the disease, this lack of coverage will create a major health equity problem, says Toma Samantha Omofoye, a breast radiologist at the MD Anderson Cancer Center at the University of Texas. "The disparities in cancer are due to issues that affect the entire healthcare system. That is why access to early and frequent screening mammograms is an important element in the fight against health disparities," she adds. For some people, however, even annual screenings may be insufficient. The widespread use of mammography has also raised awareness of the difficulties associated with dense breasts. Women who have dense breasts (generally young women) have more fibrous and connective tissue that provides structural support to the breast. This tissue is denser than fat and glands and appears white on mammograms. Dense breasts are not a problem in themselves, explains Shah, but make it more difficult to identify potential tumors on a mammogram. That is why doctors have begun to encourage women with high breast density, which is more common in younger women, to have additional imaging tests (MRI and ultrasound) in addition to their annual mammograms. To alleviate the burden of screening, scientists are working on the development of new, more accessible breast cancer screening technologies. This is the case of Canan Dagdeviren, an engineer at the MIT Media Lab, who is designing a portable ultrasound device that women can use with their everyday bra. She sketched her prototype at the bedside of her dying aunt, whose breast cancer occurred between semestral mammograms. When Dagdeviren's aunt detected changes, her cancer was too advanced to be treated. Dagdeviren states that women could use her device every month, every week, or even every day as part of their routine, as an ultrasound only takes one or two minutes. "Early detection is the key to survival. Our calculations show that this technology has the potential to save 12 million lives per year worldwide," she says. And she does not want to stop at breast cancer. Other types of tumors, such as prostate cancer, could also be detected using portable ultrasound. Even though researchers like Dagdeviren continue to develop tomorrow's screening tools, O’Connell asserts that simply knowing one's own body and being attentive to changes remains one of the most important strategies in cancer detection. "It is important to know what is normal for you to notice if something has changed," she emphasizes.