Breast Cancer Mortality in African-American and Non-Hispanic White Women by Molecular Subtype and Stage at Diagnosis: A Population-Based Study

Abstract

Background Higher breast cancer mortality rates for African-American than non-Hispanic white women are well documented; however, it remains uncertain if this disparity occurs in disease subgroups defined by tumor molecular markers and stage at diagnosis. We examined racial differences in outcome according to subtype and stage in a diverse, population-based series of 103,498 patients. Methods We obtained data for all invasive breast cancers diagnosed 1/1/2005-12/31/2012 and followed through 12/31/2012 among 93,760 non-Hispanic white and 9,738 African-American women in California. Molecular subtypes were categorized according to tumor expression of hormone receptor (HR, based on estrogen and progesterone receptors) and human epidermal growth factor receptor 2 (HER2). Cox proportional hazards models were used to calculate hazard ratios (HR) and 95% confidence intervals (CI) for breast cancer-specific mortality. Results After adjustment for patient, tumor and treatment characteristics, outcomes were comparable by race for Stage I or IV cancer regardless of subtype, and HR+/HER2+ or HR-/HER2+ cancer regardless of stage. We found substantially higher hazards of breast cancer death among African-American women with Stage II/III HR+/HER2- (HR, 1.31, 95% CI, 1.03-1.65, and HR, 1.39, 95% CI, 1.10-1.75, respectively) and Stage III triple-negative cancers relative to whites. Conclusions There are substantial racial/ethnic disparities among patients with Stages II/III HR+/HER2- and Stage III triple-negative breast cancers but not for other subtype and stage. Impact These data provide insights to assess barriers to targeted treatment (e.g. trastuzumab or endocrine therapy) of particular subtypes of breast cancer among African-American patients.

Outcome Disparities in African American Compared with European American Women with ER +HER 2- Tumors Treated within an Equal-Access Health Care System

“…nih.gov/nuccore/NG_009001.2). were found to have less favorable outcomes than EAW, 11 and, in the general population, AAW are more likely to be diagnosed at a later stage, which has been attributed to less frequent and longer intervals between screening and delays between diagnosis and treatment. 27 Within the military health care system, however, receipt of surveillance mammography did not differ significantly between non-Hispanic Whites and minority populations, 28 which may account for the >50% of…”

“…9 Survival disparities in patients with ER+HER2-tumors have OutcOme Disparities in african american cOmpareD with eurOpean american wOmen with er+her2-tumOrs treateD within an equal-access health care system Outcomes Disparities in Breast Cancer -Costantino et al also been reported for AAW with stage II/III or p53-tumors diagnosed at 50-64 years. 10,11 Evaluation of response to neoadjuvant therapy found that AAW with HR+ tumors had significantly inferior outcomes than EAW, including higher risk of recurrence and death, despite similar treatments and rates of pathologic response. 12 These data suggest that survival disparities within the ER+HER2-subtype may be a contributing factor to the overall higher breast cancer mortality in AAW.…”

Breast cancer survival by molecular subtype: a population-based analysis of cancer registry data

“…These include race, which has been shown to affect the risk of hormone-receptor-negative cancers 25,26 and survival within subtypes; [27][28][29] tobacco use, which has been associated with increased risk of hormone-receptor-negative cancers in postmenopausal women; 30 obesity, which has been linked with an increased risk of hormone-receptor-positive cancers [31][32][33] and, for premenopausal women, triple-negative cancers; 34,35 and reproductive factors such as age at menarche, parity, oral contraceptive use and breastfeeding history, which have also been shown to affect the risk of hormone-receptor-positive cancers. 30,31 Including these variables in our analysis may have adjusted the hazard ratios.…”

Racial disparities in individual breast cancer outcomes by hormone-receptor subtype, area-level socio-economic status and healthcare resources

“…The disparity is partly explained by differential access to high-quality screening and healthcare resources [4, 5], factors that operate at both individual and area levels and have been shown to influence stage at diagnosis and receipt of guideline-adherent treatment [6], and therefore survival [7]. Underlying biological differences in breast cancer between Black and White women may also be an underlying cause of disparities in outcomes, particularly in mortality rates [8–10], as Black women are more likely to be diagnosed with aggressive, hormone-receptor (HR)-negative subtypes [10–17]. …”

“…Recent advances in molecular epidemiology provide evidence for racial differences in the aggressiveness and survival of breast cancer by HR subtype [8, 10]. When classified according to the presence or absence of tumor markers of estrogen receptor (ER), progesterone receptor (PR), and human epidermal receptor-2 (Her2), patients diagnosed with the HR-negative subtypes (ER−, PR−, and/or Her2−) experience the lowest survival rates compared with patients diagnosed with HR-positive (ER+, PR+, and/or Her2+) subtypes [10].…”