Epigenetic Determinants of Racial Disparity in Breast Cancer: Looking beyond Genetic Alterations

Socioecologic Factors and Racial Differences in Breast Cancer Multigene Prognostic Scores in US Women

Importance

Disproportionately aggressive tumor biology among non-Hispanic Black women with early-stage, estrogen receptor (ER)-positive breast cancer contributes to racial disparities in breast cancer mortality. It is unclear whether socioecologic factors underlie racial differences in breast tumor biology.

Objective

To examine individual-level (insurance status) and contextual (area-level socioeconomic position and rural or urban residence) factors as possible mediators of racial and ethnic differences in the prevalence of ER-positive breast tumors with aggressive biology, as indicated by a high-risk gene expression profile.

Design, Setting, and Participants

This retrospective cohort study included women 18 years or older diagnosed with stage I to II, ER-positive breast cancer between January 1, 2007, and December 31, 2015. All data analyses were conducted between December 2022 and April 2023.

Main Outcomes and Measures

The primary outcome was the likelihood of a high-risk recurrence score (RS) (≥26) on the Oncotype DX 21-gene breast tumor prognostic genomic biomarker.

Results

Among 69 139 women (mean [SD] age, 57.7 [10.5] years; 6310 Hispanic [9.1%], 274 non-Hispanic American Indian and Alaskan Native [0.4%], 6017 non-Hispanic Asian and Pacific Islander [8.7%], 5380 non-Hispanic Black [7.8%], and 51 158 non-Hispanic White [74.0%]) included in our analysis, non-Hispanic Black (odds ratio [OR], 1.33; 95% CI, 1.23-1.43) and non-Hispanic American Indian and Alaska Native women (OR, 1.38; 95% CI, 1.01-1.86) had greater likelihood of a high-risk RS compared with non-Hispanic White women. There were no significant differences among other racial and ethnic groups. Compared with non-Hispanic White patients, there were greater odds of a high-risk RS for non-Hispanic Black women residing in urban areas (OR, 1.35; 95% CI, 1.24-1.46), but not among rural residents (OR, 1.05; 95% CI, 0.77-1.41). Mediation analysis demonstrated that lack of insurance, county-level disadvantage, and urban vs rural residence partially explained the greater odds of a high-risk RS among non-Hispanic Black women (proportion mediated, 17%; P < .001).

Conclusions and Relevance

The findings of this cohort study suggest that the consequences of structural racism extend beyond inequities in health care to drive disparities in breast cancer outcome. Additional research is needed with more comprehensive social and environmental measures to better understand the influence of social determinants on aggressive ER-positive tumor biology among racial and ethnic minoritized women from disadvantaged and historically marginalized communities.

Racial and Ethnic Disparities in the Diagnosis and Treatment of Thyroid Disease

CONTEXT

There are differences in diagnosis, treatment, and outcomes for thyroid between racial and ethnic groups that contribute to disparities. Identifying these differences and their causes are the key to understanding and reducing disparities in presentation and outcomes in endocrine disorders.

EVIDENCE ACQUISITION

The present study reviews original studies identifying and exploring differences between benign and malignant thyroid diseases. A PubMed, Web of Science, and Scopus search was conducted for English-language studies using the terms "thyroid," "thyroid disease," "thyroid cancer," "race," "ethnicity," and "disparities" from inception to December 31, 2022.

EVIDENCE SYNTHESIS

Many racial and ethnic disparities in the diagnosis, presentation, treatment, and outcomes of thyroid disease were found. Non-White patients are more likely to have a later time to referral, to present with more advanced disease, to have more aggressive forms of thyroid cancer, and are less likely to receive the appropriate treatment than White patients. Overall and disease-specific survival rates are lower in Black and Hispanic populations when compared to White patients.

CONCLUSIONS

Extensive disparities exist in thyroid disease diagnosis, treatment, and outcomes that may have been overlooked. Further work is needed to identify the causes of these disparities to begin to work toward equity in the care of thyroid disease.

Ancestry and self-reported race in Brazilian breast cancer women

OBJECTIVE

This study aimed to evaluate the association between self-reported race/color and ancestry in Brazilian patients with breast cancer.

METHODS

This was an observational, transversal, epidemiological study, evaluating race and ancestry in 1,127 patients with breast cancer. For genetic ancestry, a 46-AIM-INDEL panel was used. The ancestral profile was evaluated with the Structure v.2.3.3 software. Descriptive statistics were performed. To assess differences between race and ancestry, an analysis of variance with Bonferoni adjustment was used.

RESULTS

The race distribution was 77.7% white, 17.6% brown, 4.1% black, 0.4% yellow, and 0.3% cafuse. The African ancestry proportion was significantly (p<0.001) more evident in black [0.63±0.21 (0.17-0.96)], followed by brown [0.25±0.16 (0.02-0.70)], and less frequent in white skin color. The European ancestry proportion was significantly (p<0.001) higher in white [0.72±0.17 (0.02-0.97)], followed by brown [0.57±0.19 (0.12-0.92)], yellow [0.27±0.31 (0.12-0.620], and black [0.24±0.19 (0.02-0.72)]. The Asiatic ancestry proportion is significantly (p<0.001) higher in yellow [0.48±0.51 (0.04-0.93)]. The Amerindian ancestry proportion frequency was the least frequent in all groups, and cafuse patients did not express differences between all race groups. The brown race group presented differences in African and European ancestry.

CONCLUSION

Although we found many similarities between white European ancestry, black African ancestry, and yellow Asian ancestry, there is great miscegenation between patients. Although they can be labeled as having one race, they do present many ancestral genes that would allow their inclusion in another race group.

Racial Disparities in Breast Cancer Treatments and Adverse Events in the SEER-Medicare Data

Despite lower incidence rates, African American (AA) patients have shorter survival from breast cancer (BC) than white (W) patients. Multiple factors contribute to decreased survival, including screening disparities, later presentation, and access to care. Disparities in adverse events (AEs) may contribute to delayed or incomplete treatment, earlier recurrence, and shortened survival. Here, we analyzed the SEER-Medicare dataset, which captures claims from a variety of venues, in order to determine whether the cancer care venues affect treatment and associated adverse events. We investigated a study population whose claims are included in the Outpatient files, consisting of hospital and healthcare facility venues, and a study population from the National Claims History (NCH) files, consisting of claims from physicians, office practices, and other non-institutional providers. We demonstrated statistically and substantively significant venue-specific differences in treatment rates, drugs administered, and AEs from treatments between AA and W patients. We showed that AA patients in the NCH dataset received lower rates of treatment, but patients in the Outpatient dataset received higher rates of treatment than W patients. The rates of recorded AEs per treatment were higher in the NCH setting than in the Outpatient setting in all patients. AEs were consistently higher in AA patients than in W patients. AA patients had higher comorbidity indices and were younger than W patients, but these variables did not appear to play roles in the AE differences. The frequency of specific anticancer drugs administered in cancer- and venue-specific circumstances and their associated AEs varied between AA and W patients. The higher AE rates were due to slightly higher frequencies in the administration of drugs with higher associated AE rates in AA patients than in W patients. Our investigations demonstrate significant differences in treatment rates and associated AEs between AA and W patients with BC, depending on the venues of care, likely contributing to differences in outcomes.

Reduced Racial Disparity as a Result of Survival Improvement in Prostate Cancer

Prostate cancer is a cancer type associated with a high level of racial and socioeconomic disparities as reported by many previous studies. However, the changes in these disparities in the past two decades have not been systematically studied. In this study, we investigated the Surveillance Epidemiology End Results (SEER) data for prostate cancer patients diagnosed during 2004-2018. African Americans and Asians showed significantly better and worse cancer-specific survival (CSS), respectively, compared to non-Hispanic white individuals after adjusting for confounding factors such as age and cancer stage. Importantly, the data indicated that racial disparities fluctuated and reached the highest level during 2009-2013, and thereafter, it showed a substantial improvement. Such a change cannot be explained by the improvement in early diagnosis but is mainly driven by the differential improvement in CSS between races. Compared with Asians and non-Hispanic whites, African American patients achieved a more significant survival improvement during 2014-2018, while no significant improvement was observed for Hispanics. In addition, the SEER data showed that high-income patients had significantly longer CSS than low-income patients. Such a socioeconomic disparity was continuously increasing during 2004-2018, which was caused by the increased survival benefits of the high-income patients with respect to the low-income patients. Our study suggests that more efforts and resources should be allocated to improve the treatment of patients with low socioeconomic status.

Breast cancer survival and the health system in Brazil: an analysis of public and private healthcare

Background

The incidence of breast cancer is increasing globally; however, survival outcomes vary and are lower in developing countries.

Methods

We analyzed the 5- and 10-year survival rates for breast cancer according to the type of healthcare insurance (public vs. private) in a referral center for cancer care in the Brazilian southeast region. This hospital-based cohort study included 517 women diagnosed with invasive breast cancer between 2003 and 2005. The Kaplan-Meier method was used to estimate the probability of survival, and the Cox proportional hazards regression model was used to assess prognostic factors.

Results

The 5- and 10-year breast cancer survival rates were as follows: private healthcare service survival rate of 80.6% (95% CI 75.0-85.0) and 71.5% (95% CI 65.4-77.1), respectively, and public healthcare service survival rate of 68.5% (95% CI 62.5-73.8) and 58.5% (95% CI 52.1-64.4), respectively. The main factors associated with the worst prognosis were lymph node involvement in both healthcare services and tumor size >2 cm only in public health services. The use of hormone therapy (private) and radiotherapy (public) was associated with the best survival rates.

Conclusions

The survival discrepancies found between health services can be explained mainly by the difference in the stage of the disease at the time of diagnosis, indicating inequalities in access to the early detection of breast cancer.

PLK1 and AURKB phosphorylate survivin differentially to affect proliferation in racially distinct triple-negative breast cancer

Protein diversity due to alternative mRNA splicing or post-translational modifications (PTMs) plays a vital role in various cellular functions. The mitotic kinases polo-like kinase 1 (PLK1) and Aurora B (AURKB) phosphorylate survivin, an inhibitor of apoptosis (IAP) family member, thereby regulating cell proliferation. PLK1, AURKB, and survivin are overexpressed in triple-negative breast cancer (TNBC), an aggressive breast cancer subtype. TNBC is associated with high proliferative capacity, high rates of distant metastasis, and treatment resistance. The proliferation-promoting protein survivin and its activating kinases, PLK1 and AURKB, are overexpressed in TNBC. In this study, we investigated the role of survivin phosphorylation in racial disparities in TNBC cell proliferation. Analysis of TCGA TNBC data revealed higher expression levels of PLK1 (P = 0.026) and AURKB (P = 0.045) in African Americans (AAs; n = 41) than in European Americans (EAs; n = 86). In contrast, no significant racial differences in survivin mRNA or protein levels were observed. AA TNBC cells exhibited higher p-survivin levels than EA TNBC cells. Survivin silencing using small interfering RNAs significantly attenuated cell proliferation and cell cycle progression in AA TNBC cells, but not in EA TNBC cells. In addition, PLK1 and AURKB inhibition with volasertib and barasertib significantly inhibited the growth of AA TNBC xenografts, but not of EA TNBC tumors. These data suggest that inhibition of PLK1 and AURKB suppresses cell proliferation and tumor growth, specifically in AA TNBC. These findings suggest that targeting survivin phosphorylation may be a viable therapeutic option for AA patients with TNBC.

Decolonising medical knowledge - The case of breast cancer and ethnicity in the UK

National and global efforts have led to significant improvements in breast health and diagnosis, globally (Lukong, 2017). These achievements, however, are not even. Focusing on the case of breast cancer in the UK, we argue that enduring forms of medical racism leave Black women more vulnerable to advanced forms of the disease, explaining higher mortality rates and later-stage diagnosis. In particular, we show how a lack of dedicated policy, inadequate data collection, and a lack of representation conspire to place Black women at additional and unnecessary risk of worse breast cancer outcomes. We thus propose key recommendations to address the ethnic disparities in and make steps to decolonise breast cancer care. These are early screening for at-risk groups, community-led interventions, and more and better representation of Black women and their risks in breast cancer resources.

A Comprehensive Review on Multifaceted Mechanisms Involved in the Development of Breast Cancer Following Adverse Childhood Experiences (ACEs)

BACKGROUND AND AIM OF THE WORK

Adverse Childhood Experiences (ACEs) may give rise to harmful effects on health throughout life. Epigenetic changes explain how preexisting risk factors may contribute to produce altered biological responses and cancer risk. The main aim of the review is to summarize studies examining the means in which Adverse Childhood Experiences (ACEs) can modulate individual vulnerability to breast cancer (BC) development through multifaceted mechanisms.

METHODS

Studies selection, data extraction, and assessments agreed to PRISMA criteria. We included original research with clinical samples following BC interventions, investigating potential mechanisms linking ACEs and BC in adults.

RESULTS

From the 3321 papers found, nine articles involving 2931 participants were selected. All studies included ACEs retrospective assessments and psychological measures, and seven of them considered biomarkers. Individuals exposed to greater ACEs were at increased BC risk compared with individuals with no ACEs. Associations were found between child abuse and/or neglect, depression, perceived stress, fatigue, and plasma levels of cytokines interleukin (IL-6), C-reactive protein (CRP), soluble tumor necrosis factor receptor type II (sTNF-RII), interleukin IL-1 receptor antagonist (IL-1ra), and psycho-physiological adjustments that may lead to BC.

CONCLUSIONS

Exposure to multiple ACEs appears a risk factor for BC development in adulthood. Although the clinical relevance of findings such as this is ambiguous, the review added evidence for a link between the presence of childhood adversity and BC occurrence, pointing to psychological, hormonal, and immunological dysregulations.

Racial Disparity in Quadruple Negative Breast Cancer: Aggressive Biology and Potential Therapeutic Targeting and Prevention

Simple Summary

Quadruple negative breast cancer (QNBC), a subgroup of triple negative BC, has emerged as a highly aggressive BC subtype that disproportionately afflicts and impacts Black/African-American (AA) women. In this article, we review molecular distinctions in Black/AA and White/European-American (EA) QNBC biology as well as address potential non-genetic risk factors that could be underlying this racially disparate burden. We aim to provide deeper insight and provide a framework for novel discovery of actionable therapeutic targets and identify lifestyle changes to improve outcomes for Black/AA QNBC patients.

Abstract

Black/African-American (AA) women, relative to their White/European-American (EA) counterparts, experience disproportionately high breast cancer mortality. Central to this survival disparity, Black/AA women have an unequal burden of aggressive breast cancer subtypes, such as triple-negative breast cancer (ER/PR-, HER2-wild type; TNBC). While TNBC has been well characterized, recent studies have identified a highly aggressive androgen receptor (AR)-negative subtype of TNBC, quadruple-negative breast cancer (ER/PR-, HER2-wildtype, AR-; QNBC). Similar to TNBC, QNBC disproportionately impacts Black/AA women and likely plays an important role in the breast cancer survival disparities experienced by Black/AA women. Here, we discuss the racial disparities of QNBC and molecular signaling pathways that may contribute to the aggressive biology of QNBC in Black/AA women. Our immediate goal is to spotlight potential prevention and therapeutic targets for Black/AA QNBC; ultimately our goal is to provide greater insight into reducing the breast cancer survival burden experienced by Black/AA women.

Association of antipsychotic use with breast cancer: a systematic review and meta-analysis of observational studies with over 2 million individuals

AIMS

Despite reports of an elevated risk of breast cancer associated with antipsychotic use in women, existing evidence remains inconclusive. We aimed to examine existing observational data in the literature and determine this hypothesised association.

METHODS

We searched Embase, PubMed and Web of Science™ databases on 27 January 2022 for articles reporting relevant cohort or case-control studies published since inception, supplemented with hand searches of the reference lists of the included articles. Quality of studies was assessed using the Newcastle-Ottawa Scale. We generated the pooled odds ratio (OR) and pooled hazard ratio (HR) using a random-effects model to quantify the association. This study was registered with PROSPERO (CRD42022307913).

RESULTS

Nine observational studies, including five cohort and four case-control studies, were eventually included for review (N = 2 031 380) and seven for meta-analysis (N = 1 557 013). All included studies were rated as high-quality (seven to nine stars). Six studies reported a significant association of antipsychotic use with breast cancer, and a stronger association was reported when a greater extent of antipsychotic use, e.g. longer duration, was operationalised as the exposure. Pooled estimates of HRs extracted from cohort studies and ORs from case-control studies were 1.39 [95% confidence interval (CI) 1.11-1.73] and 1.37 (95% CI 0.90-2.09), suggesting a moderate association of antipsychotic use with breast cancer.

CONCLUSIONS

Antipsychotic use is moderately associated with breast cancer, possibly mediated by prolactin-elevating properties of certain medications. This risk should be weighed against the potential treatment effects for a balanced prescription decision.

Exosomal Metabolic Signatures Are Associated with Differential Response to Neoadjuvant Chemotherapy in Patients with Breast Cancer

Neoadjuvant chemotherapy (NAC) is commonly used in breast cancer (BC) patients to increase eligibility for breast-conserving surgery. Only 30% of patients with BC show pathologic complete response (pCR) after NAC, and residual disease (RD) is associated with poor long-term prognosis. A critical barrier to improving NAC outcomes in patients with BC is the limited understanding of the mechanisms underlying differential treatment outcomes. In this study, we evaluated the ability of exosomal metabolic profiles to predict NAC response in patients with BC. Exosomes isolated from the plasma of patients after NAC were used for metabolomic analyses to identify exosomal metabolic signatures associated with the NAC response. Among the 16 BC patients who received NAC, eight had a pCR, and eight had RD. Patients with RD had 2.52-fold higher exosome concentration in their plasma than those with pCR and showed significant enrichment of various metabolic pathways, including citrate cycle, urea cycle, porphyrin metabolism, glycolysis, and gluconeogenesis. Additionally, the relative exosomal levels of succinate and lactate were significantly higher in patients with RD than in those with pCR. These data suggest that plasma exosomal metabolic signatures could be associated with differential NAC outcomes in BC patients and provide insight into the metabolic determinants of NAC response in patients with BC.