The updated draft recommendation from the US Preventive Services Task Force (USPSTF) that would lower the recommended start age for routine screening mammograms by a decade for all average-risk women is not justified, experts argue in a “dissenting view” published in The New England Journal of Medicine.
The proposed change would affect more than 20 million US women, and it’s “hard to see any potential benefits associated with lowering the starting age,” coauthor Steven Woloshin, MD, with the Dartmouth Cancer Center, Lebanon, New Hampshire, said in an NEJM podcast.
Back in May, when USPSTF released the draft recommendation, task force member John Wong, MD, with Tufts Medical Center, Boston, told Medscape, “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.”
But, according to Woloshin, there is no recent evidence that mortality from breast cancer is increasing in young women.
In fact, the US has seen a steady decrease in breast cancer mortality, especially among younger women. Breast cancer mortality among women under 50 “has been cut in half over the past 30 years,” Woloshin, alongside Karsten Juhl Jørgensen, MD, DMedSci; Shelley Hwang, MD, MPH; and H. Gilbert Welch, MD, MPH, explained.
Another wrinkle: The task force did not base its recent recommendation on randomized trial data. In fact, there have been no new randomized trials of screening mammography for women in their 40s since 2016. Instead, the task force relied on statistical models to “estimate what might happen if the starting age were lowered,” Woloshin and colleagues said.
Relying on a statistical model, however, “is problematic because it has some very optimistic assumptions about the benefit of mammography,” Woloshin said in the podcast. For instance, the models assume that screening mammography reduces breast cancer mortality by about 25%.
That 25% reduction, he noted, is “far greater than what’s reported in the meta-analyses of the available randomized trials,” Woloshin explained. The meta-analyses report about a 16% reduction for all the trials combined and an estimated 13% for trials at low risk of bias. But “even these meta-analyses are likely to overstate the effect of screening since the trials were done before the major advances in treatment,” Woloshin added.
In their own calculations, Woloshin and colleagues found that lowering the screening age to 40 came with a small potential benefit and a substantial risk for harm.
Combing data from the National Cancer Institute, the team reported that the risk for death for women in their 40s from any cause over the next 10 years was about 3% whether or not they received their biennial mammogram.
The risk for death from breast cancer in that time was 0.23% with mammograms — about 2 in every 1000 women — and 0.31% without. “That’s 1 less breast cancer death per 1000 women screened for 10 years,” Woloshin said.
Put another way, with mammography screening, “the chance of not dying from breast cancer over the next 10 years increases from 99.7% to 99.8%,” Woloshin said.
The benefit is arguably small, while the harms appear quite significant, Woloshin said.
About 36% of women who begin screening at age 40 would have at least one false alarm over 10 years, and almost 7% would have a false alarm requiring a biopsy in that timeframe.
Ease or Exacerbate Racial Disparity?
Another argument that the USPSTF highlighted for lowering the screening age: Research indicates that Black women get breast cancer at younger ages and are more likely to die of the disease compared with White women.
Woloshin and coauthors, however, also took issue with the view that lowering the screening age could reduce disparities between Black and White women.
“There’s no question that there are substantial differences between Black and White women in terms of breast cancer mortality, but there’s actually very little disparity in breast cancer screening — about 60% of Black and White women in their 40s are screened regularly in the United States,” Woloshin explained in the podcast.
Therefore, it’s “really hard to imagine” how recommending the same intervention to both groups could possibly reduce the disparity, he said.
“The disparity is not a reflection of screening. It reflects differences in cancer biology,” he added. “Black women are at higher risk for more aggressive, fast-growing cancers that are less likely to be caught by screening and unfortunately are less likely to benefit from treatment.”
Earlier screening would also not address the problems facing poor women, who tend to be disproportionately Black, such as lower quality of available medical services, follow-up delays after abnormal scans, treatment delays, and less use of adjuvant therapy, Woloshin cautioned.
In Woloshin’s view, lowering the screening age, which broadens the eligible population, may actually “exacerbate problems contributing to disparity by diverting resources toward expanded screening rather than doing what we know works by ensuring that high-quality treatments are more readily accessible to poor women with breast cancer.”
Reconsider the Change?
Because task force recommendations are so influential, Woloshin and his colleagues worry that mammography screening for women in their 40s will probably become a performance measure.
“Our concern is that rather than fostering informed decisions, clinicians and practices are going to be judged and rewarded and punished based on compliance with this quality metric,” Woloshin said.
That’s a problem, he noted, “because women should be able to make the decision for themselves rather than having this be a public health imperative, which is imposed by physicians and practices who are incentivized to meet a quality metric.”
The hope, said Woloshin, is that this prospective piece will help influence the task force to “reconsider the recommendation, because we think that the bottom line is that their models are insufficient to support a new imperative. The benefits are really limited, and there are really common and important harms for healthy women.”
The comment period for the draft recommendation is now closed, and a final decision from the task force is forthcoming.
This research had no funding. Woloshin has no relevant disclosures.
N Engl J Med. Published September 21, 2023. Full text
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