Starting Mammograms at Age 40: Will Women Benefit?

Last April, the US Preventive Services Task Force (USPSTF) revised their breast cancer screening guidelines to recommend average-risk women start their screening mammograms at age 40, instead of age 50, and continue every other year until age 74. 

The USPSTF’s recent recommendations align with those from major organizations, including the National Comprehensive Cancer Network and the American College of Radiology. The latest update comes from the American College of Obstetricians and Gynecologists (ACOG), which recommended a start age of 40 and continued screening either annually or every 2 years.

For USPSTF, the decision to recommend the earlier screening age, instead of keeping the choice an individualized one, was largely driven by the steady rise in breast cancer diagnoses among women in their 40s, alongside evidence that Black women are more likely to get breast cancer younger and die from the disease compared with White women. 

But is this recommendation to screen earlier a change for the better? 

Opinions vary.

USPSTF member John Wong, MD, chief of clinical decision making and a primary care physician at Tufts Medical Center in Boston, believes the new recommendation is the right move.

“It is now clear that screening every other year starting at age 40 has the potential to save about 20% more lives among all women and there is even greater potential benefit for Black women, who are much more likely to die from breast cancer,” Wong told Medscape last year. 

However, in a recent Viewpoint in JAMA Internal Medicine, experts from the University of California San Francisco expressed their reservations about shifting the recommended screening age a decade earlier.

The trio — Karla Kerlikowske, MD, Laura Esserman, MD, and Jeffrey Tice, MD — called the new recommendations “surprising” given the lack of new randomized control trial data to support the change as well as data that show breast cancer deaths have been decreasing among women, including younger women. 

More specifically, breast cancer deaths for women under 50 have decreased from 5.9 to 3.9 per 100,000 individuals between 2000 and 2020 — a decline that can likely be attributed to better treatments rather than increased screening effectiveness, the Viewpoint authors said.

However, moving the screening age earlier would not markedly improve survival for most women, the authors argued. According to USPSTF modeling, starting mammograms at age 40 instead of 50 could avert only 1.3 additional breast cancer deaths per 1000 women screened biennially and 1.8 additional breast cancer deaths among Black women.

Starting screening at 40, however, does come with an array of potential harms. These include 65 more benign biopsies per 1000 women screened, 1 in 2 women with a false-positive mammography result (503 per 1000), and 1 in 500 women with an over-diagnosed breast cancer, meaning the cancer would not have become clinically evident in their lifetime. 

The use of digital breast tomosynthesis can slightly reduce the number of false-positives and benign biopsies compared to older mammography techniques, but these small improvements did not sway the overall pro-con assessment for the Viewpoint authors.

“False-positive results require additional imaging and are associated with anxiety for patients,” the authors noted. “Women who have benign biopsies may experience the potential adverse effects of biopsies, such as bleeding, infection, and scarring unnecessarily; and over-diagnosis may lead to unnecessary treatment.”

Kenneth Lin, MD, MPH, family physician and associate director of the Lancaster General Hospital Family Medicine Residency in Pennsylvania, agreed that starting mammograms at age 40 is not a change for the better. 

Lin and colleagues conducted an analysis based on data from the USPSTF’s 2016 breast cancer screening report that similarly found 1 additional breast cancer death prevented per 1000 women screened starting at 40 vs 50, at a cost of 576 more false-positive results, 67 more benign breast biopsies, and 2 women diagnosed and treated unnecessarily. 

Overall, “there is no compelling evidence to change our clinical approach to breast cancer screening for women in their 40s: individual decision-making based on patient preferences and values,” Lin wrote in a recent Medscape commentary. 

But several experts not involved in the USPSTF recommendations agree with the change. 

The updated recommendation to begin mammograms at age 40 for women at average risk “aligns with accumulating data suggesting that earlier and more frequent screening can save more lives, and is widely seen as a positive step,” said Lisa Abramson, MD, a radiologist specializing in breast imaging with Mount Sinai Health System and Icahn School of Medicine at Mount Sinai, New York City.

Melissa Fana, MD, a breast surgical oncologist at NYU Langone Health, agreed that the revised recommendation is justified and “will undoubtedly save lives.” 

“The recent change in the screening recommendation was meant to be inclusive, and provide women, particularly women aged 40 to 49 the opportunity to screen with mammography,” Fana said.

One major argument in favor of earlier screening is that it will help address racial inequities in breast cancer diagnoses, treatment, and deaths. Despite a 5% lower incidence of breast cancer, Black women are more likely to be diagnosed with distant-stage cancer or more aggressive breast cancer subtypes, such as triple-negative, compared with White women, and are more likely to die from breast cancer.

“We hope that the earlier initiation of mammography screening across the board will have a great net benefit in outcomes for Black women especially, who have been shown to have the poorest outcomes when it comes to breast cancer, in part because of long-standing inequities in social determinants of health,” said Cherie C. Hill, MD, FACOG, an OB/GYN at Emory Healthcare in Atlanta, who coauthored the recent ACOG recommendations.

The Viewpoint authors Kerlikowske, Esserman and Tice agreed that Black women may benefit more from earlier screening. However, earlier screening does not address the underlying disparities in treatment and follow-up care for Black women, and it is unclear whether screening alone will help improve breast cancer mortality rates for Black women, the authors noted.

There is one place where experts seem to align: the importance of educating patients about their personal risk. 

The Viewpoint authors favor a risk-based approach to help women decide whether to start screening before age 50. 

“Engaging women in informed decision-making based on their invasive and advanced breast cancer risk would be a patient-centered approach toward tailored screening, informing when to consider starting screening and how often to screen,” the experts wrote. 

For a woman to truly make an educated decision on whether she would like to screen or wait after age 40, she would at least need to know what her specific lifetime risk of developing breast cancer is, not the average risk is for American women in general, Fana told Medscape Medical News. 

“Risk assessment calculators are widely available and include factors such as family history and reproductive history, and this information can evolve over time and affect lifetime risk,” Fana noted. But “some women just do not get this information.”

Abramson explained that OB-GYNs and primary care physicians will likely play a larger role in the early assessment of breast cancer risk, including discussions about genetic testing and personal risk factors starting as early as age 25. 

“For clinicians, the emphasis may be on educating patients about their individual risk, ensuring timely mammograms, and referring higher-risk individuals for further testing or consultations with specialists,” Abramson added. 

Esserman reported being a Blue Cross Medical Advisory Panel member, an uncompensated board member of Quantum Leap Healthcare Collaborative, which funds the I-SPY trial through the University of California, San Francisco, and having an investigator-initiated trial for high-risk ductal carcinoma in situ (DCIS) funded through UCSF by Moderna for a DCIS phase 1 study. Tice and Kerlikowske reported receiving grants from the National Cancer Institute outside the submitted work. Abramson and Fana have no relevant disclosures.