Neighborhood characteristics and breast tumor methylation: using epigenomics to explore cancer outcome disparities

Neighborhood Disinvestment Predicts Shorter Cancer Survival Time among Black Women Diagnosed with Invasive Breast Cancer

BACKGROUND

Observed neighborhood disinvestment is a chronic social determinant that is understudied in relation to cancer outcomes. This study investigated associations between neighborhood disinvestment, stage at diagnosis, and breast cancer-specific survival (BCSS) time.

METHODS

Individual-level data included 844 women, diagnosed 2013 to 2019, from the Women's Circle of Health Follow-up Study, a population-based cohort of breast cancer survivors self-identifying as Black or African American. Neighborhood disinvestment was from a virtual audit of six indicators-garbage, graffiti, dumpsters, building conditions, yard conditions, and abandoned buildings-within 14,671 Google Street View streetscapes estimated at residential addresses using Universal Kriging. We fit accelerated failure time models of BCSS time as functions of neighborhood disinvestment by stage, adjusted for covariates (sociodemographic, lifestyle, and tumor- and treatment-related factors). Participants not experiencing an event at the end of follow-up (August 13, 2023) were right-censored.

RESULTS

With a median follow-up time of 89 months, there were 91 breast cancer-specific deaths. Disinvestment and stage statistically interacted (P < 0.01). For stage III and stage II diagnoses, BCSS time decreased by 27% (95% confidence interval, 1%, 48%) and 37% (95% confidence interval, 5%, 58%), respectively, with each SD increase in disinvestment after adjustment for covariates. There was little evidence of associations between disinvestment and survival time among stages I and IV.

CONCLUSIONS

The tumor stage-dependent association between greater neighborhood disinvestment and shorter survival time could reflect chronic stress exposures suspected to adversely accumulate over time.

IMPACT

Neighborhood disinvestment might be an important, independent marker of social disadvantage impacting breast cancer survival.

Impact of Structural Racism and Social Determinants of Health on Disparities in Breast Cancer Mortality

The striking ethnic and racial disparities in breast cancer mortality are not explained fully by pathologic or clinical features. Structural racism contributes to adverse conditions that promote cancer inequities, but the pathways by which this occurs are not fully understood. Social determinants of health, such as economic status and access to care, account for a portion of this variability, yet interventions designed to mitigate these barriers have not consistently led to improved outcomes. Based on the current evidence from multiple disciplines, we describe a conceptual model in which structural racism and racial discrimination contribute to increased mortality risk in diverse groups of patients by promoting adverse social determinants of health that elevate exposure to environmental hazards and stress; these exposures in turn contribute to epigenetic and immune dysregulation, thereby altering breast cancer outcomes. Based on this model, opportunities and challenges arise for interventions to reduce racial and ethnic disparities in breast cancer mortality.

Social Genomic Determinants of Health: Understanding the Molecular Pathways by Which Neighborhood Disadvantage Affects Cancer Outcomes

PURPOSE

Neighborhoods represent complex environments with unique social, cultural, physical, and economic attributes that have major impacts on disparities in health, disease, and survival. Neighborhood disadvantage is associated with shorter breast cancer recurrence-free survival (RFS) independent of individual-level (race, ethnicity, socioeconomic status, insurance, tumor characteristics) and health system-level determinants of health (receipt of guideline-concordant treatment). This persistent disparity in RFS suggests unaccounted mechanisms such as more aggressive tumor biology among women living in disadvantaged neighborhoods compared with advantaged neighborhoods. The objective of this article was to provide a clear framework and biological mechanistic explanation for how neighborhood disadvantage affects cancer survival.

METHODS

Development of a translational epidemiological framework that takes a translational disparities approach to study cancer outcome disparities through the lens of social genomics and social epigenomics.

RESULTS

The social genomic determinants of health, defined as the physiological gene regulatory pathways (ie, neural/endocrine control of gene expression and epigenetic processes) through which contextual factors, particularly one's neighborhood, can affect activity of the cancer genome and the surrounding tumor microenvironment to alter disease progression and treatment outcomes.

CONCLUSION

We propose a novel, multilevel determinants of health model that takes a translational epidemiological approach to evaluate the interplay between political, health system, social, psychosocial, individual, and social genomic determinants of health to understand social disparities in oncologic outcomes. In doing so, we provide a concrete biological pathway through which the effects of social processes and social epidemiology come to affect the basic biology of cancer and ultimately clinical outcomes and survival.

Neighborhood Deprivation and DNA Methylation and Expression of Cancer Genes in Breast Tumors

Importance

The biological processes that underlie the association of neighborhood environment with chronic diseases, such as cancer, remain poorly understood.

Objective

To determine whether differences in breast tissue DNA methylation are associated with neighborhood deprivation among Black and White women with breast cancer.

Design, Setting, and Participants

This cross-sectional study collected breast tissue from women undergoing surgery for breast cancer between January 1, 1993, and December 31, 2003. Participants were recruited through the University of Maryland Medical Center, with additional collection sites at Baltimore-area hospitals. Data analysis was performed from March 1 through December 1, 2022.

Exposure

Year 2000 census tract-level socioeconomic deprivation measured via neighborhood deprivation index (NDI) as a standardized score, with Black and White race being ascertained through self-report.

Main Outcome and Measures

The primary outcome was tissue DNA methylation using genome-wide measurements. The secondary outcome was tissue gene expression.

Results

Participants included 185 women with breast cancer (110 Black [59.5%], 75 White [40.5%]). Mean (SD) age at surgery was 56.0 (14.1) years. Neighborhood deprivation was higher for Black women than for White women (Mean [SD] NDI, 2.96 [3.03] for Black women and -0.54 [1.91] for White women; difference, -3.50; 95% CI, -4.22 to -2.79; P < .001). In unstratified analysis, 8 hypomethylated CpG sites were identified as associated with the NDI, including sites in 2 tumor suppressor genes, LRIG1 and WWOX. Moreover, expression of the 2 genes inversely correlated with neighborhood deprivation. In the race-stratified analysis, the negative correlation between the LRIG1 gene body CpG site cg26131019 and the NDI remained significant in Black women. A neighborhood deprivation-associated decrease in gene expression was also observed for LRIG1 and WWOX in tumors from Black women.

Conclusions and Relevance

In this study, high neighborhood deprivation was associated with differences in tissue DNA methylation and gene expression among Black women. These findings suggest that continued investment in public health interventions and policy changes at the neighborhood level may help to remedy biological alterations that could make minoritized populations more susceptible to chronic diseases.

From Race to Racism and Disparities to Equity: An Actionable Biopsychosocial Approach to Breast Cancer Outcomes

PURPOSE

Racial disparities in outcomes of breast cancer in the United States have widened over more than 3 decades, driven by complex biologic and social factors. In this review, we summarize the biological and social narratives that have shaped breast cancer disparities research across different scientific disciplines in the past, explore the underappreciated but crucial ways in which these 2 strands of the breast cancer story are interwoven, and present 5 key strategies for creating transformative interdisciplinary research to achieve equity in breast cancer treatment and outcomes.

DESIGN

We first review the key differences in tumor biology in the United States between patients racialized as Black versus White, including the overrepresentation of triple-negative breast cancer and differences in tumor histologic and molecular features by race for hormone-sensitive disease. We then summarize key social factors at the interpersonal, institutional, and social structural levels that drive inequitable treatment. Next, we explore how biologic and social determinants are interwoven and interactive, including historical and contemporary structural factors that shape the overrepresentation of triple-negative breast cancer among Black Americans, racial differences in tumor microenvironment, and the complex interplay of biologic and social drivers of difference in outcomes of hormone receptor positive disease, including utilization and effectiveness of endocrine therapies and the role of obesity. Finally, we present 5 principles to increase the impact and productivity of breast cancer equity research.

RESULTS

We find that social and biologic drivers of breast cancer disparities are often cyclical and are found at all levels of scientific investigation from cells to society. To break the cycle and effect change, we must acknowledge and measure the role of structural racism in breast cancer outcomes; frame biologic, psychosocial, and access factors as interwoven via mechanisms of cumulative stress, inflammation, and immune modulation; take responsibility for the impact of representativeness (or the lack thereof) in genomic and decision modeling on the ability to accurately predict the outcomes of Black patients; create research that incorporates the perspectives of people of color from inception to implementation; and rigorously evaluate innovations in equitable cancer care delivery and health policies.

CONCLUSIONS

Innovative, cross-disciplinary research across the biologic and social sciences is crucial to understanding and eliminating disparities in breast cancer outcomes.

Redlining-associated methylation in breast tumors: the impact of contemporary structural racism on the tumor epigenome

Purpose

Place-based measures of structural racism have been associated with breast cancer mortality, which may be driven, in part, by epigenetic perturbations. We examined the association between contemporary redlining, a measure of structural racism at the neighborhood level, and DNA methylation in breast tumor tissue.

Methods

We identified 80 Black and White women diagnosed and treated for a first-primary breast cancer at Emory University Hospitals (2008-2017). Contemporary redlining was derived for census tracts using the Home Mortgage Disclosure Act database. Linear regression models were used to calculate the association between contemporary redlining and methylation in breast tumor tissue. We also examined epigenetic age acceleration for two different metrics, regressing β values for each cytosine-phosphate-guanine dinucleotide (CpG) site on redlining while adjusting for covariates. We employed multivariable Cox-proportional hazards models and 95% confidence intervals (CI) to estimate the association between aberrant methylation and mortality.

Results

Contemporary redlining was associated with 5 CpG sites after adjustment for multiple comparisons (FDR<0.10). All genes were implicated in breast carcinogenesis, including genes related to inflammation, immune function and stress response (ANGPT1, PRG4 and PRG4). Further exploration of the top 25 CpG sites, identified interaction of 2 sites (MRPS28 and cg11092048) by ER status and 1 site (GDP1) was associated with all-cause mortality. Contemporary redlining was associated with epigenetic age acceleration by the Hannum metric (β=5.35; CI 95%=0.30,10.4) and showed positive but non-significant correlation with the other clock.

Conclusion

We identified novel associations between neighborhood contemporary redlining and the breast tumor DNA methylome, suggesting that racist policies leading to inequitable social and environmental exposures, may impact the breast tumor epigenome. Additional research on the potential implications for prognosis is needed.

Survival Disparities in US Black Compared to White Women with Hormone Receptor Positive-HER2 Negative Breast Cancer

Black women in the US have significantly higher breast cancer mortality than White women. Within biomarker-defined tumor subtypes, disparate outcomes seem to be limited to women with hormone receptor positive and HER2 negative (HR+/HER2-) breast cancer, a subtype usually associated with favorable prognosis. In this review, we present data from an array of studies that demonstrate significantly higher mortality in Black compared to White women with HR+/HER2-breast cancer and contrast these data to studies from integrated healthcare systems that failed to find survival differences. Then, we describe factors, both biological and non-biological, that may contribute to disparate survival in Black women.

Association of Race and Area Deprivation With Breast Cancer Survival Among Black and White Women in the State of Georgia

Importance

Increasing evidence suggests that low socioeconomic status and geographic residence in disadvantaged neighborhoods contribute to disparities in breast cancer outcomes. However, little epidemiological research has sought to better understand these disparities within the context of location.

Objective

To examine the association between neighborhood deprivation and racial disparities in mortality among Black and White patients with breast cancer in the state of Georgia.

Design, Setting, and Participants

This population-based cohort study collected demographic and geographic data from patients diagnosed with breast cancer between January 1, 2004, and February 11, 2020, in 3 large health care systems in Georgia. A total of 19 580 patients with breast cancer were included: 12 976 from Piedmont Healthcare, 2285 from Grady Health System, and 4319 from Emory Healthcare. Data were analyzed from October 2, 2020, to August 11, 2022.

Exposures

Area deprivation index (ADI) scores were assigned to each patient based on their residential census block group. The ADI was categorized into quartile groups, and associations between ADI and race and ADI × race interaction were examined.

Main Outcomes and Measures

Cox proportional hazards regression models were used to compute hazard ratios (HRs) and 95% CIs associating ADI with overall mortality by race. Kaplan-Meier curves were used to visualize mortality stratified across racial and ADI groups.

Results

Of the 19 580 patients included in the analysis (mean [SD] age at diagnosis, 58.8 [13.2] years), 3777 (19.3%) died during the course of the study. Area deprivation index contributed differently to breast cancer outcomes for Black and White women. In multivariable-adjusted models, living in a neighborhood with a greater ADI (more deprivation) was associated with increased mortality for White patients with breast cancer; compared with the ADI quartile of less than 25 (least deprived), increased mortality HRs were found in quartiles of 25 to 49 (1.22 [95% CI, 1.07-1.39]), 50 to 74 (1.32 [95% CI, 1.13-1.53]), and 75 or greater (1.33 [95% CI, 1.07-1.65]). However, an increase in the ADI quartile group was not associated with changes in mortality for Black patients with breast cancer (quartile 25 to 49: HR, 0.81 [95% CI, 0.61-1.07]; quartile 50 to 74: HR, 0.91 [95% CI, 0.70-1.18]; and quartile ≥75: HR, 1.05 [95% CI, 0.70-1.36]). In neighborhoods with an ADI of 75 or greater, no racial disparity was observed in mortality (HR, 1.11 [95% CI, 0.92-1.36]).

Conclusions and Relevance

Black women with breast cancer had higher mortality than White women in Georgia, but this disparity was not explained by ADI: among Black patients, low ADI was not associated with lower mortality. This lack of association warrants further investigation to inform community-level approaches that may mitigate the existing disparities in breast cancer outcomes in Georgia.

Association Between Residence in Historically Redlined Districts Indicative of Structural Racism and Racial and Ethnic Disparities in Breast Cancer Outcomes

Importance

Historical structural racism may be associated with racial, ethnic, and geographic disparities in breast cancer outcomes, but few studies have investigated these potential relationships.

Objective

To test associations among historical mortgage lending discrimination (using 1930s Home Owners' Loan Corporation [HOLC] redlining data), race and ethnicity, tumor clinicopathologic features, and survival among women recently diagnosed with breast cancer.

Design, Setting, and Participants

This cohort study used a population-based, state cancer registry to analyze breast tumor clinicopathology and breast cancer-specific death among women diagnosed from 2008 to 2017 and followed up through 2019. Participants included all primary, histologically confirmed, invasive breast cancer cases diagnosed among women aged at least 20 years and who resided in a HOLC-graded area of New Jersey. Those missing race and ethnicity data (n = 61) were excluded. Data were analyzed between June and December 2021.

Exposures

HOLC risk grades of A ("best"), B ("still desirable"), C ("definitely declining"), and D ("hazardous" [ie, redlined area]).

Main Outcomes and Measures

Late stage at diagnosis, high tumor grade, triple-negative subtype (lacking estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 expression), breast cancer-specific death.

Results

Among a total of 14 964 women with breast cancer, 2689 were Latina, 3506 were non-Latina Black, 7686 were non-Latina White, and 1083 were other races and ethnicities (non-Latina Asian/Pacific Islander/Native American/Alaska Native/Hawaiian or not otherwise specified); there were 1755 breast cancer-specific deaths. Median follow-up time was 5.3 years (95% CI, 5.2-5.3 years) and estimated 5-year breast cancer-specific survival was 88.0% (95% CI, 87.4%-88.6%). Estimated associations between HOLC grade and each breast cancer outcome varied by race and ethnicity; compared with residence in HOLC redlined areas, residence in HOLC areas graded "best" was associated with lower odds of late-stage diagnosis (odds ratio [OR], 0.34 [95% CI, 0.22-0.53]), lower odds of high tumor grade (OR, 0.72 [95% CI, 0.57-0.91]), lower odds of triple-negative subtype (OR, 0.67 [95% CI, 0.47-0.95]), and lower hazard of breast cancer-specific death (hazard ratio, 0.48 [95% CI, 0.35-0.65]), but only among non-Latina White women. There was no evidence supporting associations among non-Latina Black or Latina women.

Conclusions and Relevance

Compared with redlined areas, current residence in non-redlined areas was associated with more favorable breast cancer outcomes, but only among non-Latina White women. Future studies should examine additional factors to inform how historical structural racism could be associated with beneficial cancer outcomes among privileged racial and ethnic groups.