Emerging racial disparities in US breast cancer mortality

Age-standardized breast cancer mortality (death per 100,000 women per year) was calculated using SEER * Stat software version 8.3.9.2 based on the underlying cause of death reported on the death certificate. rice field. Prior to 1990, the Census Bureau provided county-level population estimates according to three racial categories: whites, blacks, and other races. Therefore, white races include Hispanic and non-Hispanic whites, and black races include Hispanic and non-Hispanic blacks. Modified and updated by DeSantis and others.¹

In the United States, age-adjusted breast cancer mortality is approximately 40% higher in black women than in non-hispanic white women (2014-2018), despite the lower incidence of black women. Mortality per 100,000 women is 27.7 vs. 20.0) (125.8 vs. 139.2 cases per 100,000 women) (see table). Therefore, it may be surprising to many clinicians that before 1980, breast cancer mortality was slightly lower in black women than in white women (see). graph). Since 1980, mortality has fluctuated sharply and this inequality continues.^1,2

What caused the differences in breast cancer mortality between races in the 1980s? The age-duration-cohort (APC) model provides important clues as it can be used to distinguish between changes in mortality based on age at death, year of death (calendar period), or year of birth (birth cohort). To do.² Calendar-based trends reflect changes in exposure that affect the entire population at specific times, such as access to new medical interventions, while birth cohort-based trends are risk factors for people born at different times. Reflects the fluctuation of.²

In a previous study, one of us reported that the APC model showed significant racial differences in breast cancer mortality over a calendar period rather than a birth cohort.² Therefore, the emergence of racial disparities in breast cancer mortality may be due to the calendar period effect rather than the birth cohort effect. This means that the introduction of new medical interventions was probably a facilitator. In the 1980s, two medical interventions (mammography screening and adjuvant endocrine therapy) were widely practiced in the United States for breast cancer management, and racial disparities in access to and their effectiveness of these interventions probably contributed to mortality differences. Caused.² Black women are more likely to have less health insurance or inadequate coverage than white women, limiting access to mammography screening and negatively impacting therapeutic decision-making. For example, in the 1980s, mammography screening rates were significantly lower for black women than for white women, but they are now the same.²

Both mammography screening and endocrine therapy benefit patients with hormone receptor (HR) -positive breast cancer. This is the most common subtype for both black and white women.^2,3 Mammography screening preferentially detects HR-positive tumors, which are slower than HR-negative tumors and therefore spend more time in the preclinical stage, and target endocrine therapy.^2,3 In contrast, HR-negative tumors are often detected as symptomatic (ie, palpable) cancers between mammography examinations.³ HR-negative cancers include triple-negative (ie, estrogen receptor negative, progesterone receptor negative, and human epidermal growth factor receptor type 2). [HER2]– Negative) Breast cancer, an aggressive subtype that is more often diagnosed among late-stage and younger women than other breast cancer subtypes. Black women have a 65% higher incidence of HR-negative breast cancer (29.3 vs. 17.7 per 100,000 women between 2014 and 2018) and triple-negative breast cancer rates compared to non-hispanic white women. 81% higher (21.9 vs 12.1 cases per 100,000 women); Therefore, black women benefit less from the introduction of mammography screening and adjuvant endocrine therapy.¹

Some researchers have found that genetic factors are HR-negative and triple-negative for black women, as most black women in the United States have their ancestors in western sub-Saharan Africa, where HR-negative breast cancer is common. It suggests explaining the high proportion of breast cancer imbalances. ..^Four However, if genetic factors are the only determinant of hormone receptor biology, the incidence of HR-negative breast cancer in different racial groups in the United States should be relatively stable in recent years. However, between 1992 and 2016, the incidence of HR-negative breast cancer decreased in women of all races in the United States, and there was considerable variability in the rate of decrease between racial groups and women of the same race in different regions. was.^Five The decline was slowest among black women, with less decline among white women from less wealthy areas than white women from wealthier areas. This suggests that social determinants of health (ie, structural racism and the constructed environment) affect access and quality as well as health care, as well as the development of HR-negative breast cancer. ..^Five

Since 1990, overall breast cancer mortality has decreased by 40% in the United States. Screening, adjuvant systemic therapy, and reduced incidence of HR-negative cancer contribute to lower mortality in both black and white women, as in the case of HR-negative cancer incidence. The rate of decline is uneven. .. If all people with breast cancer benefit equally from effective medical interventions, racial differences in mortality for individual tumor subtypes primarily reflect differences in incidence. However, breast cancer data from the National Cancer Center’s surveillance, epidemiology, and end-result registries cannot be explained by differences in incidence alone, and are substantial races for both HR-positive and HR-negative cancer mortality. It shows that there is a disparity.

Mortality in patients with specific tumor subtypes reflects incidence, case confirmation, and treatment. Despite a 22% lower incidence in black women, HR-positive breast cancer mortality is 19% higher in black women than in white women, and HR-negative breast cancer mortality is more than twice as high as in white women. — Parallax significantly greater than the 65% relative difference in incidence. The mortality gap between both tumor subtypes is timely and high quality for black women, although there are differences and differences in biological factors between patients with specific tumor subtypes, such as differences in grade and HER2 status. It indicates that you may face substantial barriers to access to medical care. Depending on your response and compliance with treatment within a group of patients, you can also partially explain the disparity.

The differences in breast cancer mortality between black and white women vary significantly within the United States. This partially reflects the difference in the extent to which the state promotes universal access to quality health care.¹ Lack of or inadequate coverage of health insurance limits access to timely and effective treatment²According to data from the Kaiser Family Foundation, more than 11% of non-aged blacks are uninsured, compared to about 8% of non-aged whites. Universal insurance can reduce disparities in the treatment of all subtypes of cancer, including triple-negative breast cancer. Therefore, removing barriers to medical access can reduce racial disparities in breast cancer mortality.

Prior to the 1980s, overall breast cancer mortality in the United States was very stable for decades, and the focus of treatment was mastectomy. The widespread use of screening mammography and adjuvant systemic therapy, which began in the 1980s, was an important turning point, after which breast cancer mortality was significantly reduced. However, the complication of implementing these medical interventions was the emergence of large racial disparities in breast cancer mortality in the United States. Black women benefit less from these interventions than white women, have a significantly higher incidence of HR-negative tumors, and generally have a poorer prognosis than other tumors. From 2014 to 2018, a total of 56% of the difference in breast cancer deaths between black and white women could be due to HR-negative cancer. We believe that supporting research on the prevention and treatment of triple-negative breast cancer is a national priority as it is essential to reduce the resulting racial disparity and reduce global breast cancer mortality. Overall breast cancer incidence remains lower in black women than in white women in the United States, so ensuring universal access to quality health care will help race breast cancer mortality in the United States. The gap can be narrowed significantly.