medwireNews: Initiating biennial breast screening for Black women at age 40 years rather than the US standard of 50 years could substantially reduce Black–White breast cancer mortality disparities without increasing harms, modelling data suggest.
Writing in the Annals of Internal Medicine, Christina Hunter Chapman (University of Michigan, Ann Arbor, USA) and co-authors say their study “highlights an important concept in health equity: Equivalent interventions may yield inequitable outcomes.”
Using data from the Cancer Intervention and Surveillance Modeling Network, Chapman and team evaluated nine breast cancer screening strategies that varied by initiation age (40, 45, and 50 years) and screening interval (annual, biennial, and combinations of the two by age) until age 74 years in 100 million simulated life histories.
The models included race-specific inputs for breast cancer subtype distribution, breast density, mammography performance, age-, stage-, and subtype-specific treatment effects, and non-breast cancer mortality.
Chapman and team report that the most efficient strategy for Black women, yielding 16.4 life–years gained (LYG) per mammogram versus no screening, was biennial screening from age 45 years.
However, the most equitable strategy, which yielded benefit–harm trade-offs closest to benchmark values for screening White women biennially from age 50 to 74 years, was biennial screening from age 40 years. In this case, there were 15.0 LYG per mammogram compared with 14.5 LYG per mammogram for White women initiating screening at age 50 years.
Biennial screening from age 40 years also resulted in the largest mortality reduction for Black women, with 32% more LYG and 19% more breast cancer deaths averted than would be expected with biennial screening from age 50 years, but this comes at a cost of 45% more mammograms and 52% more false–positive results.
Nonetheless, the researchers calculated that if Black women initiated biennial screening at age 40 years rather than age 50 years, 57% of the racial disparity in breast cancer mortality, or 1.88 of the 3.29 excess deaths per 1000 people, would be removed.
Furthermore, the findings were sensitive to assumptions about treatment disparities. “The less effective treatment was for Black women, the more intensively Black women could be screened before tradeoffs fell short of those experienced by White women,” Chapman et al remark.
But they stress that while “earlier screening may partially mitigate the effect of treatment disparities, it should not supersede efforts to achieve treatment equity.”
The authors also acknowledge that “racism, and not race, is likely the primary driver of many of the disparities” in their study and that this is “difficult to change and will not be resolved in the near term.”
They therefore conclude: “We reduce harm by compensating for this with enhanced screening. Implementation of equitable screening represents a practical, sustainable, high-impact solution for reducing disparities that could be implemented in the short term.”
In an accompanying editorial, David Jones from Harvard University in Cambridge, Massachusetts, USA, considers the “possible harms of race-based medicine” and says that the use of crude race categories can be problematic.
He says: “If we think human differences are important and should inform medical practice, then we need to invest the effort required to map and understand those differences.”
medwireNews is an independent medical news service provided by Springer Healthcare Ltd. © 2021 Springer Healthcare Ltd, part of the Springer Nature Group
Ann Intern Med 2021; doi:10.7326/M20-6506
Ann Intern Med 2021; doi:10.7326/M21-3804