A new approach to breast screening suggests that all women should have a baseline assessment of breast density with mammography at age 40.
The result would then be used to confirm further screening, with annual screening starting at age 40 for medium-risk women with dense breasts, and screening every 2 years starting at age 50 for women without dense breasts. .
Such an approach would be cost-effective and offer a more focused risk-based strategy for early detection of breast cancer compared to conventional practices, say the authors, led by Tina Shih, PhD, University of Texas MD Anderson Cancer Center, Houston.
Their modeling study was published online today in the History of internal treatments.
However, experts writing in accompanying edits are not persuaded. Karla Kerlikowske, MD, and Kirsten Bibbins-Domingo, MD, PhD, both from the University of California, San Francisco, show that not all women with a dense breast are at increased risk for breast cancer. They caution not to rely on breast density alone when determining screening strategies, and state that age and other risk factors must also be considered.
Proposed new approach
Current recommendations from the U.S. Consecration Services Task Force (USPSTF) suggest that women in their 40s may undergo a screening mammogram based on their personal preference, Shih explained to them Medscape Medical News.
However, these recommendations do not take into account the increased risk that breast density poses the risk of breast cancer – and a mammogram is the only way for women to experience breast density. “If you follow [current] instructions, you wouldn’t know about your breast density until age 45 or 50, ”she said.
“But what if you knew about breast density earlier and then put it into action – would that make a difference?” This was the question her team wanted to investigate.
For their study, the authors described women with dense breasts as those with the C System for Breast Imaging and Data Reporting (BI-RADS) (heterogeneously dense breasts) and category D (very thick breasts).
The team used a computer model to compare seven breast screening strategies:
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No screening
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Three-year mammography from 50 to 75 years (T50)
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Biennial mammography from age 50 to 75 years (B50)
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Serial annual mammography from ages 50 to 75 for women with dense breasts at age 50, and three-year screening from ages 50 to 75 for women without breastfeeding at age 50 (SA50T50)
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Serial annual mammography from ages 50 to 75 for women with dense breasts at age 50, and biennial screening from ages 50 to 75 for those without breastfeeding at age 50 (SA50B50)
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Serial annual mammography from ages 40 to 75 for women with dense breasts at age 49, and three-year screening from ages 50 to 75 for those without breastfeeding at age 40 (SA40T50)
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Serial annual mammography from ages 40 to 75 for women with dense breasts at age 40, and biennial mammography for women aged 50 to 75 without dense breasts at age 40 (SA40B50)
Compared to a no-screening strategy, the average number of mammography sessions throughout a woman’s life would increase from 7 mammograms per lifetime for the minimum screening (T50) to 22 mammograms per lifetime for the most intensive screening record, the team reports.
Compared to no screening, screening reduced breast cancer deaths from 8.6 per 1000 women (T50) to 13.2 per 1000 women (SA40B50).
A cost-effectiveness study showed that the proposed new approach (SA40B50) resulted in an increased cost-effectiveness ratio of $ 36,200 per year of quality-adjusted life (QALY) compared to the two-screen screening strategy. currently proposed annual. This is well within the threshold of paying $ 100,000 per QALY accepted by society at large, the authors point out.
On the other hand, false-positive results and overdiagnosis would increase, the authors note.
The average number of faults would increase from 141.2 per 1000 women who underwent the minimum three-year mammogram screening (T50) to 567.3 per 1000 women with the new procedure (SA40B50).
Levels of overdiagnosis would also go up from a low of 12.5% to a high of 18.6%, they add.
“With this study, we are not saying that everyone should start screening at age 40, we are just saying, do baseline mammography at age 40, know the status of breast density and then we can try to change the screening schedule based on individual risk, “Shih stressed.
“Compared to other screening strategies examined in our study, this strategy is associated with the greatest reduction in breast cancer death and is cost effective, [although it] includes the largest screening mammograms in a woman ‘s life and higher rates of false – positive results and overdiagnosis, “the authors conclude.
A fundamental problem with this approach
The fundamental problem with this approach of confirming the risk of breast density measurement – and on the basis of one reading – is that not all women with dense breasts are at greater risk for breast cancer, the -editor says.
Kerlikowske and Bibbins-Domingo show, in fact, that only about a quarter of women with dense breasts are at high risk for invasive cancer lost within a year of a negative mammogram and these women can be identified using a Breast Cancer Research Consortium risk model.
“This observation means that most women with dense breasts can undergo screening every two years and do not have to consider annual screening or additional imaging,” the editors write.
“Therefore, we warn against using breast density alone to determine if a woman is at high risk for breast cancer,” they confirm.
Another option is to focus on overall risk in order to select screening strategies, they suggest. For example, most guidelines recommend screening from age 50 to 74 – so identifying women in their 40s who are at the same risk for women aged 50 to 59 is one way to get their -out who might benefit from starting screening earlier, the editors are keeping an eye on.
“Therefore, women who have a first-degree relationship with breast cancer or a history of breast biopsy may be offered screening in their 40s and, if mammography shows a dense breast, they could continue proceed with biennial screening through their 40s, “the editors monitor.” Such women with nondense breasts may resume screening every two years at the age of 50. ”
Shih said Medscape Medical News she did not agree with the editors’ suggestion that physicians could focus on total breast cancer risk in order to select an appropriate screening strategy for individual patients.
“What we are proposing is, ‘We do not carry out a baseline assessment at the age of 40 so that women know about their breast density instead of waiting until they are older,'” she said.
“But what the editors are proposing is a strategy that could be even more cost-effective,” she said, adding that Kerlikowske and Bibbins-Domingo estimate that only a quarter of women with dense breasts at high risk for breast cancer apparently limiting breast density directly to those women with BI-RADs category “D” – very thick breasts.
But as Shih points out, women with both category C and category D breast density are at a higher risk for breast cancer, so avoiding women with lower levels of breast cancer is not. breast density still treats that they have a higher-than-normal risk for breast cancer.
“Universal screening strategies are becoming more difficult to operate as we learn more and more about breast cancer, so people are starting to talk about screening strategies based on patient risk classification. , “Shih noted.
“It will be more difficult to implement strategies like this but it seems to be the right approach,” she said.
The study was funded by the National Cancer Institute. Shih will report on donations from the National Cancer Institute during the conduct of the study and personal fees from Pfizer and AstraZeneca outside of the work submitted. Kerlikowske is an unpaid consultant for GRAIL for the STRIVE study. Bibbins-Domingo did not disclose any material financial relationships.
In Inside Med. Published online February 8, 2021.
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