A new study suggests that tailoring breast cancer screening to a woman’s individual risk can be as safe as yearly mammograms while reducing unnecessary testing for some and better targeting of care for others.
Breast cancer is one of the leading causes of cancer death for women around the world, affecting about 1 in 8 women in the United States. While the authors of the study suggest their findings could influence screening recommendations, some other researchers and public health experts worry that personalized screening could cause certain cancers to be missed, especially if assessments underestimate a woman’s risk or don’t work well for all populations. They have argued that annual screening, while imperfect, is the most reliable and equitable approach.
But there are those researchers and cancer specialists who say screening everyone, every year often leads to women at low-risk for breast cancer being tested more than necessary, while women at higher risk may not be tested enough. Because of this imbalanced mismatch, they say tailoring screening to individual risk is a more effective use of resources and leads to better outcomes.
The study published Friday in JAMA was the first randomized clinical trial to assess the impact of a risk-based screening approach, but it revealed one limitation: Relatively few women followed the recommended screening schedules. Still, the study found that shifting screening approaches was just as safe and led to fewer unnecessary tests, especially for women at low risk.
“Screening has fallen short in many ways,” said Laura J. Esserman, the study’s lead author and director of the University of California, San Francisco Breast Care Center. Current screening practices cost about $13 billion a year, she said, adding “for that kind of resource we should be thinking about how to make it better.”
The risk-assessment approach puts breast cancer more in line with screening for cardiac disease, where doctors use scores to help them determine when to intervene with medication and other forms of treatment, she said.
Esserman, a breast surgical oncologist, said there is a need for new guidelines and has spoken with members of the U.S. Preventive Services Task Force, which influences medical guidance and what procedures and screenings are covered by insurance. She expects resistance but said she also believes changes will come — eventually.
Robert Smith, a senior vice president at the American Cancer Society who focuses on early cancer detection science, said the study addresses the pressing issue of “under screening people who need more aggressive monitoring and over screening those who don’t need it.”
While confident the U.S. is moving in the direction of clinical guidelines changes, he said a large number of details still need to be studied. Risk assessment would not be a one-time thing, he said, noting it would need to be updated periodically based on advances in genetic discoveries, updates to family history, hormone replacement therapy or weight changes.
“Clinical guidelines never have and never will change overnight,” he said, adding that there will be women who are worried about any reduction in their recommended screening who would prefer in fact to be screened more regularly. “That’s going to be the real challenge,” he said, “to have the data to be convincing that our guidance for a woman in her individual case doesn’t leave her any less safe.”
The biggest barrier to acceptance of any new clinical guidelines is public psychology — women are so used to being told to get a mammogram each year starting at 40, said Steven Isakoff, co-clinical director of breast oncology at the Mass General Brigham Cancer Institute, who called the study results “very exciting” and a “positive first step.”
“We have promoted annual mammograms for so long that it’s going to be a challenge to message the opposite way,” he said. “I think the uptake could be slow and cautious.”
He pointed out that one limitation of study is that the demographics skewed more toward White, college-educated women than the general U.S. population.
The lack of diversity matters because it does not consider differences in tumor biology, said Vivian Jolley Bea, a board-certified breast surgical oncologist who is director of the breast program at New York Presbyterian-Brooklyn Methodist Hospital and faculty at NewYork-Presbyterian Weill Cornell Medical Center. Black women are twice as likely to be diagnosed with a more aggressive form of breast cancer, she said, and they have a 40 percent higher mortality.
“It’s not just family history. It’s not just breast density. It’s tumor biology, and so if we’re not including those people in a randomized clinical trial that can then inform how we screen people moving forward, then we’re doing a disservice,” she said, noting the study assumes a level of access to genetic testing that most people don’t have.
Debra L. Monticciolo, section chief of breast imaging at Dartmouth Hitchcock Medical Center, said she was troubled by the data on how often study participants adhered to the suggested mammogram schedules. For high-risk groups and low-risk groups alike, she said “it was really poor” and essentially the same.
That seems to imply, she said, that some women who were told to get fewer mammograms may have felt more comfortable getting more and those who were told to go in more often weren’t doing so. She said that makes it difficult to make any comparisons between the two groups.
Monticciolo said that while the study’s plan for personalizing mammogram schedules is laudable it would be very hard to do in practice due to the burden it puts on breast health specialists. For this to be worthwhile, she said “you’d want to show it’s a better approach, not just a non-inferior approach, and it’s hard to tell from this data that it is.”
Two researchers from Australia, writing in an editorial that also published Friday in JAMA, said the study strengthens confidence that risk-based breast cancer screening can be done safely but leaves open questions about whether it can work at scale. They pointed to the fact that few women in the large, real-world trial followed the screening recommendations, saying it makes the effectiveness of the approach remain “uncertain.”
The study followed 28,400 women for five years. The women, who were on average 54 years old, were divided into one of two groups — annual breast cancer screening, or screening based on their personal level of risk. They were recruited online from all 50 states and were only eligible if they had never had breast cancer, a preventative double mastectomy or a noninvasive cancer that’s confined to milk ducts.
Women in the annual group were told to get a mammogram every year starting at age 40. Women in the risk-based group received screening recommendations tailored to their genetic makeup and other clinical factors. Depending on their risk, they might start screening at 50, get mammograms every one or two years, or alternate between mammograms and MRI scans every six months.
The study found that the risk-based screening approach was just as safe as annual screening because it did not lead to more advanced breast cancers, and biopsy rates and the detection of slightly earlier-stage cancers were similar between the two groups.
Women who are at a high risk of getting breast cancer — including women with genetic mutations, dense breasts, or family histories — were screened earlier, more often and with imaging tools that are better at detecting certain cancers and monitoring changes, the study found. And women in the study group overall had fewer mammograms, which was especially true for women who were at low-risk of getting breast cancer. But as women’s risk-level increased, so did their use of mammograms, MRIs, biopsies and other cancer detection methods.
The use of risk-reducing medications, also known as chemoprevention drugs, almost doubled, among the women at highest risk for breast cancer, going from five to 10 percent, the study found.
That — how many high-risk women opted for prevention therapy — was one of the things two Australian researchers found especially promising about the study, they wrote in their editorial. Nancy N. Baxter, a clinical epidemiologist and general surgeon who is deputy dean of Research Centres in the Faculty of Medicine and Health at University of Sydney, and Kelly-Anne Phillips, a medical oncologist and breast-cancer specialist at the Peter MacCallum Cancer Centre and an honorary professorial fellow at the University of Melbourne, wrote that the results show how personalized prevention can make a difference.
They noted that women who were told that being overweight, drinking alcohol and not being physically active increase breast cancer risk were more likely to report cutting back on alcohol and increasing their physical activity three months later.
The trial also helped reduce one of the biggest barriers to getting chemoprevention drugs that can reduce risk: knowing your level of risk, which they said, most women do not. That’s “a barrier that risk-based screening directly addresses,” they wrote. Though guidelines recommend the medications for women at increased risk of breast cancer, they wrote that the “uptake in practice remains strikingly low.” And because so few people began taking the medications during the trial, they wrote that use “will not substantially improve without a limited degree of coordination” between screening services and those who prescribe prevention medications.
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