Women Age 55 and Up Still Choosing Annual Breast Screening

Professional societies differ in weighing the benefits and harms of mammography screening, and guidelines vary on the age of screening initiation and cessation. For example, some recommend starting at age 40, 45, or 50 years and ceasing at age 75 years or with < 10 years’ life expectancy. They also differ on recommended screening frequency, that is, annual vs biennial.

A recent research letter in Annals of Internal Medicine suggested that annual mammography may be being done unnecessarily in some groups. It found that more than 75% of women receiving mammography screening in the past 2 years reported a mammogram the past year. That suggested the possibility of overscreening despite guidelines such as those of the US Preventive Services Task Force recommending biennial screening for average-risk women aged 55 years or older. 

The findings emerged from a study by Mara A. Schonberg, MD, MPH, Division of General Internal Medicine at Beth Israel Deaconess Medical Center in Boston, and colleagues who examined mammography screening patterns in US women aged 40-84 years in the past year vs the past 1-2 years.

“Unfortunately, there is very little data on outcomes for screening annually vs biennially,” Schonberg told Medscape Medical News. Because none of the randomized controlled trials of mammography screening included women aged 75 years or older, the benefit of screening in that group is uncertain, she continued. “Meanwhile, there are harms that increase with age such as overdiagnosis leading to overtreatment.”

Some clarification may come from the WISDOM study, a multicenter randomized trial comparing personalized screening with annual screening among women aged 40-74 years.

In her research on improving shared decision-making for women aged 75 years or older, Schonberg developed a decision aid; she found that many women in this group continued screening annually despite the uncertain benefit. “I was curious if what I was seeing locally was true nationwide that many women are screened annually despite guidelines recommending biennial screening, especially as women age,” she said.

Schonberg was somewhat surprised at the small decrease in yearly screening by older age or life expectancy. “This is likely because the American College of Radiology recommends annual screening and once women have a mammogram, breast imaging centers tend to send all women, regardless of age or health, a reminder annually to get a mammogram,” she said.

Study Specifics

Her group used deidentified data from the 2019 and 2021 National Health Interview Survey (NHIS) to analyze a final sample of 20,034 women with no breast cancer history, representing 97.3 million US women. Among women aged 65-84 years, the investigators also examined screening in the past year (vs 1-2 years) by 10-year life expectancy using a validated index.

The mean age of participants was 58.7 years, and 66.1% were non-Hispanic White women. Overall, 68.1% reported mammography screening in the past 2 years, of which an unexpected 75.2% reported screening in the past year.

Among women screened in the past 2 years, those aged 40-44 and 55-74 years were more likely to report screening in the past year than women aged 45-54 or 75-84 years.

Also more likely to report screening in the past year were the following: Non-Hispanic Black women, college degree holders, the privately insured, residents of the Northeast or Midwest, married women, those with higher incomes, those reporting a wellness visit or physical in the past year, and those surveyed in 2019.

In addition, although most guidelines recommend shared decision-making or discontinuation of screening for women with a life expectancy of < 10 years or aged 75 years or older, many in these groups also reported screening in the past year.

The authors noted that non-Hispanic Black women experience greater breast cancer death than those from other racial and ethnic populations, yet in this review, non-Hispanic Black women reported the highest screening rates. That suggested to the authors that future interventions to improve breast cancer outcomes for this racial group should focus on follow-up testing and treatment rather than screening.

“Mammograms are good at finding slow-growing breast cancers early. This may explain why the few trials that have tested annual vs biennial screening find no mortality difference,” Schonberg said. “It’s reasonable to recommend biennial screening to most women, except potentially those at high risk for breast cancer. At a minimum, women should be given the opportunity to make an informed decision based on a realistic understanding of the likely outcomes.”

But a different perspective on appropriate frequency is offered by Quan Nguyen, MD, an associate professor of radiology at Baylor College of Medicine in Houston, where annual screening is the norm, an option supported, for example, by the American College of Obstetricians and Gynecologists.

Nguyen, who was not involved in the intervals study, pointed out that no decade of life accounts for more than 25% of the cancers diagnosed each year. “Some analysts have compared women in one decade of life, ages 40-49, to the combined results for all other women ages 50-79 to make it appear as if there is a sudden jump in results at the age of 50, when there are no sudden jumps,” he told Medscape Medical News. “The median age at the time of breast cancer diagnosis is 62 — meaning that half of women with breast cancer are diagnosed before age 62 and half are diagnosed afterward.”

Lisa L. Abramson, MD, an associate professor of radiology at Icahn School of Medicine at Mount Sinai in New York City, who did not participate in the study, flatly disagreed with the idea of overuse. “In all age groups, yearly mammography is still the most beneficial option,” she told Medscape Medical News. “Especially in women age 55, and even in healthy women age 75 and older, we still find breast cancers before they’re symptomatic. The earlier the detection the better the chance of less surgery and the need for treatments like radiation and chemotherapy.”

An accompanying editorial, however, agreed with the study authors that the data pointed to potential overuse, including annual vs biennial intervals and screening beyond the age when early detection would confer a mortality benefit. “Given the long-term persistence of annual mammography as the dominant interval, most patients and clinicians seem to consistently place greater weight on the potential benefits than harms of more intense screening regimens,” wrote Amy Trentham-Dietz, PhD, MS, Carbone Cancer Center and Department of Population Health Sciences at the School of Medicine and Public Health, University of Wisconsin-Madison, and colleague Brian L. Sprague, PhD, MS, University of Vermont Cancer Center and Departments of Surgery, Radiology, and Biochemistry, Larner School of Medicine, University of Vermont, Burlington, Vermont.

“Numerous evidence-based interventions are available where broader implementation could improve alignment between screening use, guidelines, a patient’s individual risk for breast cancer, and their personal preferences,” they wrote.

The editorial commentators cautioned, however, that NHIS data are susceptible to misclassification due to self-report, selection bias, and other threats to validity, and they lack measures required for breast cancer risk assessment and monitoring of screening use by risk level. Nevertheless, they said, such public health surveillance data provide a critical benchmark against which all other studies should be compared.

This research was funded by the National Institutes of Health/National Institute on Aging (NIH/NIA) and the Health Resources and Services Administration of the US Department of Health and Human Services with financial support from some nongovernmental sources. Schonberg reported receiving royalty payments from UpToDate and grant support from NIH/NIA and NIH/National Cancer Institute. The coauthors disclosed receiving support from similar government research funders but no relevant financial conflicts of interest.

Nguyen and Abramson disclosed no conflicts of interest relevant to their comments. Trentham-Dietz and Sprague reported receiving government funding support outside of the submitted work.