Breast Cancer Less Common in Black Women, So Why Do More Die?

Pam Harrison

June 20, 2022

Although breast cancer occurs less frequently in Black women compared to White women, they have a much higher risk of dying from the disease.

In the United States, age-adjusted breast cancer mortality between 2014 and 2018 was approximately 40% higher among Black women than among non-Hispanic White women.

This mortality gap likely reflects the fact that Black women face substantial barriers to obtaining timely, high-quality medical care compared with White women, lead author Ismail Jatoi, MD, PhD, University of Texas Health Science Center, San Antonio, and colleagues suggest in a recent opinion piece.

The article was published online June 18 in The New England Journal of Medicine.

When the team examined the statistics for breast cancer mortality, they found a surprise: the mortality gap between races only dates back to 1980.

Prior to 1980, mortality from breast cancer among Black women was slightly lower than White women, Jatoi and colleagues point out.

That year was a turning point in breast cancer management, as in 1980, both mammography screening and adjuvant endocrine therapy became available.

This was also when the mortality gap between the races started to show up.

It was disparities in access to the two new interventions that precipitated the divergence, as the authors suggest. Why this occurred is fairly self-evident, they comment.

"Black women are more likely than White women to lack health insurance or to have inadequate coverage, which has limited their access to mammography screening and adversely affected therapeutic decision making," researchers point out.

Moreover, both mammography screening and endocrine therapy primarily benefit patients with hormone receptor (HR)-positive breast cancer, which is equally common in Black and White patients. However, Black women have a 65% higher rate of HR-negative cancers than White women — and HR-negative tumors are often detected during the interval between mammography screening exams as palpable cancers.

Black women also have an 81% higher rate of triple-negative breast cancer, so they have benefited less from mammography screening and adjuvant endocrine therapy, both of which favor the detection and treatment of HR-positive breast cancer, the authors emphasize.

Some have suggested that the excess HR-negative breast cancer in Black women might be explained by hereditary factors. Yet as Jatoi and colleagues point out, the incidence of HR-negative breast cancer has actually been falling across all races in the United States since 1992.

However, the declines have been slower among Black women, and reductions in its incidence have been smaller among White women living in less affluent regions of the US compared with White women from more affluent regions.

These patterns suggest that social determinants of health influence not only access to and quality of healthcare but also the development of HR-negative breast cancers, as the authors observe.

"If all people with breast cancer benefited equally from effective medical interventions, racial differences in mortality for individual tumor subtypes would largely reflect differences in incidence," Jatoi and colleagues continue.

Yet the statistics show that the substantial racial disparities in mortality for both HR-positive and HR-negative cancers between Black and White women cannot be explained by differences in the incidence of either tumor alone, they write.

For example, mortality for HR-positive breast cancer is 19% higher among Black women than among White women, yet the incidence of HR-positive breast cancer is 22% lower among Black women.

Similarly, mortality from HR-negative breast cancer is over twice as high among Black women as it is among White women — a substantially larger disparity compared with the 65% relative difference in the incidence of HR-negative breast cancer between the two races.

"Universal healthcare coverage could reduce disparities in treatment for cancers of all subtypes, including triple-negative breast cancer," Jatoi and colleagues reemphasize.

"Ensuring universal access to high-quality medical care can substantially narrow the racial disparity in US breast-cancer mortality," they conclude. 

The authors have reported no relevant financial relationships.

N Engl J Med. Published online June 18, 2022. Full text

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