Deconstructing Racial and Ethnic Disparities in Breast Cancer

Global Stage Distribution of Breast Cancer at Diagnosis: A Systematic Review and Meta-Analysis

Importance

Stage at diagnosis is a key prognostic factor for cancer survival.

Objective

To assess the global distribution of breast cancer stage by country, age group, calendar period, and socioeconomic status using population-based data.

Data Sources

A systematic search of MEDLINE and Web of Science databases and registry websites and gray literature was conducted for articles or reports published between January 1, 2000, and June 20, 2022.

Study Selection

Reports on stage at diagnosis for individuals with primary breast cancer (C50) from a population-based cancer registry were included.

Data Extraction and Synthesis

Study characteristics and results of eligible studies were independently extracted by 2 pairs of reviewers (J.D.B.F., A.D.A., A.M., R.S., and F.G.). Stage-specific proportions were extracted and cancer registry data quality and risk of bias were assessed. National pooled estimates were calculated for subnational or annual data sets using a hierarchical rule of the most relevant and high-quality data to avoid duplicates.

Main Outcomes and Measures

The proportion of women with breast cancer by (TNM Classification of Malignant Tumors or the Surveillance, Epidemiology, and End Results Program [SEER]) stage group.

Results

Data were available for 2.4 million women with breast cancer from 81 countries. Globally, the proportion of cases with distant metastatic breast cancer at diagnosis was high in sub-Saharan Africa, ranging from 5.6% to 30.6% and low in North America ranging from 0.0% to 6.0%. The proportion of patients diagnosed with distant metastatic disease decreased over the past 2 decades from around 3.8% to 35.8% (early 2000s) to 3.2% to 11.6% (2015 onwards), yet stabilization or slight increases were also observed. Older age and lower socioeconomic status had the largest proportion of cases diagnosed with distant metastatic stage ranging from 2.0% to 15.7% among the younger to 4.1% to 33.9% among the oldest age group, and from 1.7% to 8.3% in the least disadvantaged groups to 2.8% to 11.4% in the most disadvantaged groups.

Conclusions and Relevance

Effective policy and interventions have resulted in decreased proportions of women diagnosed with metastatic breast cancer at diagnosis in high-income countries, yet inequality persists, which needs to be addressed through increased awareness of breast cancer symptoms and early detection. Improving global coverage and quality of population-based cancer registries, including the collection of standardized stage data, is key to monitoring progress.

Computer Vision Identifies Recurrent and Nonrecurrent Ductal Carcinoma in Situ Lesions with Special Emphasis on African-American Women

Although nonrecurrent and recurrent forms of ductal carcinoma in situ (DCIS) of the breast are observed, no evidence-based test can make this distinction. The current retrospective case-control study used archival DCIS samples stained with anti-phospho-Ser226-glucose transporter type 1 and anti-phosphofructokinase type L antibodies. Immunofluorescence micrographs were used to create machine learning models of recurrent and nonrecurrent biomarker patterns, which were evaluated in cross-validation studies. Clinical performance was assessed by holdout studies using patients whose data were not used in training. Micrographs were stratified according to the recurrence probability of each image. Recurrent patients were defined by at least one image with a probability of recurrence ≥98%, whereas nonrecurrent patients had none. These studies found no false-negatives, identified true-positives, and uniquely identified true-negatives. Roughly 20% of the microscope fields of recurrent lesions were computationally recurrent. Strong prognostic results were obtained for both white and African-American women. This machine tool provides the first means to accurately predict recurrent and nonrecurrent patient outcomes. Data indicate that at least some false-positive findings were true-positive findings that benefited from surgical intervention. The intracellular locations of phospho-Ser226-glucose transporter type 1 and phosphofructokinase type L likely participate in cancer recurrences by accelerating glucose flux, a key feature of the Warburg effect.

County characteristics associated with refusing breast cancer surgery: Evidence from the Surveillance, Epidemiology, and End Results program

BACKGROUND

Individuals' communities impact cancer disparities and are intimately related to social determinants of health. Studies show that personal factors affect treatment refusals for a potentially curable cancer, but few studies have investigated whether community-based characteristics affect the receipt of surgery.

METHODS

We used Surveillance Epidemiology and End Results Program registries from 2010 to 2015 to examine differences in rates of surgery refusal among non-Hispanic White, non-Hispanic Black, and Hispanic women diagnosed with nonmetastatic breast cancer. The community factor measures were based on county-level factors. Sociodemographic and community differences were analyzed using Pearson's χ2 tests and analysis of variance. Multivariate logistic regression of predictors of surgery refusal and the Cox proportional hazard model of disease-specific mortality were performed.

RESULTS

Surgery refusers among non-Hispanic Black and Hispanic all races lived in counties with lower rates of educational attainment, median family and household income, and higher rates of poverty, unemployment, foreign-born, language isolation, urban population, and women more than 40 years old having mammography in last 2 years. Multivariate analysis shows surgery refusal rates increased in counties having a high percentage of urban population and declined in counties with an increased percentage of less than high school level education, unemployment, and median household income. Breast cancer-specific mortality increased significantly with surgery refusal.

CONCLUSION

Residence in counties with the lowest socioeconomic status and disproportionately populated by racial and ethnic minorities is associated with surgery refusal. Given the high mortality associated with refusing surgery, culturally sensitive education on the benefits of care may be appropriate.

Racial and ethnic disparities in childhood and young adult acute lymphocytic leukaemia: secondary analyses of eight Children's Oncology Group cohort trials

BACKGROUND

Previous studies have identified racial and ethnic disparities in childhood acute lymphocytic leukaemia survival. We aimed to establish whether disparities persist in contemporaneous cohorts and, if present, are attributable to differences in leukaemia biology or insurance status.

METHODS

Patients with newly diagnosed acute lymphocytic leukaemia in inpatient and outpatient centres in the USA, Canada, Australia, and New Zealand, aged 0-30 years, who had race or ethnicity data available, enrolled on eight completed Children's Oncology Group trials (NCT00103285, NCT00075725, NCT00408005, NCT01190930, NCT02883049, NCT02112916, NCT02828358, and NCT00557193) were included in this secondary analysis. Race and ethnicity were categorised as non-Hispanic White, Hispanic, non-Hispanic Black, non-Hispanic Asian, and non-Hispanic other. Event-free survival and overall survival were compared across race and ethnicity groups. The relative contribution of clinical and biological disease prognosticators and insurance status was examined through multivariable regression models, both among the entire cohort and among those with B-cell lineage versus T-cell lineage disease.

FINDINGS

Between Jan 1, 2004, and Dec 31, 2019, 24 979 eligible children, adolescents, and young adults with acute lymphocytic leukaemia were enrolled, of which 21 152 had race or ethnicity data available. 11 849 (56·0%) were male and 9303 (44·0%) were female. Non-Hispanic White patients comprised the largest racial or ethnic group (13 872 [65·6%]), followed by Hispanic patients (4354 [20·6%]), non-Hispanic Black patients (1517 [7·2%]), non-Hispanic Asian (n=1071 [5·1%]), and non-Hispanic other (n=338 [1·6%]). 5-year event-free survival was 87·4% (95% CI 86·7-88·0%) among non-Hispanic White patients compared with 82·8% (81·4-84·1%; hazard ratio [HR] 1·37, 95% CI 1·26-1·49; p<0·0001) among Hispanic patients and 81·8% (79·3-84·0; HR 1·45, 1·28-1·65; p<0·0001) among non-Hispanic Black patients. Non-hispanic Asian patients had a 5-year event-free survival of 88·1% (95% CI 85·5-90·3%) and non-Hispanic other patients had a survival of 82·8% (76·4-87·6%). Inferior event-free survival among Hispanic patients was substantially attenuated by disease prognosticators and insurance status (HR decreased from 1·37 [1·26-1·49; p<0·0001] to 1·11 [1·00-1·22; p=0·045]). The increased risk among non-Hispanic Black patients was minimally attenuated (HR 1·45 [1·28-1·65; p<0·0001] to 1·32 [1·14-1·52; p<0·0001]). 5-year overall survival was 93·6% (91·5-95·1%) in non-Hispanic Asian patients, 93·3% (92·8-93·7%) in non-Hispanic White patients, 89·9% (88·7-90·9%) in Hispanic, 89·7% (87·6-91·4%) in non-Hispanic Black patients, 88·9% (83·2-92·7%) in non-Hispanic other patients. Disparities in overall survival were wider than event-free survival (eg, among non-Hispanic other patients, the HR for event-free survival was 1·43 [1·10-1·85] compared with 1·74 [1·27-2·40] for overall survival). Disparities were restricted to patients with B-cell acute lymphocytic leukaemia, no differences in event-free survival or overall survival were seen in the T-cell acute lymphocytic leukaemia group.

INTERPRETATION

Substantial disparities in outcome for B-cell acute lymphocytic leukaemia persist by race and ethnicity, but are not observed in T-cell acute lymphocytic leukaemia. Future studies of relapsed patients, access to and quality of care, and other potential aspects of structural racism are warranted to inform interventions aimed at dismantling racial and ethnic disparities.

FUNDING

National Cancer Institute and St Baldrick's Foundation.

Insulin resistance and racial disparities in breast cancer prognosis: a multi-center cohort study

The survival for breast cancer (BC) is improving but remains lower in Black women than White women. A number of factors potentially drive the racial differences in BC outcomes. The aim of our study was to determine if insulin resistance (defined as homeostatic model assessment for insulin resistance (HOMA-IR)), mediated part of the relationship between race and BC prognosis (defined by the improved Nottingham prognostic index (iNPI)). We performed a cross-sectional study, recruiting self-identified Black and White women with newly diagnosed primary invasive BC from 10 US hospitals between March 2013 and February 2020. Survey, anthropometric, laboratory, and tumor pathology data were gathered, and we compared the results between Black and White women. We calculated HOMA-IR as well as iNPI scores and examined the associations between HOMA-IR and iNPI. After exclusions, the final cohort was 1206: 911 (76%) White and 295 (24%) Black women. Metabolic syndrome and insulin resistance were more common in Black than White women. Black women had less lobular BC, three times more triple-negative BC, and BCs with higher stage and iNPI scores than White women (P < 0.001 for all comparisons). Fewer Black women had BC genetic testing performed. HOMA-IR mediated part of the association between race and iNPI, particularly in BCs that carried a good prognosis and were hormone receptor (HR)-positive. Higher HOMA-IR scores were associated with progesterone receptor-negative BC in White women but not Black women. Overall, our results suggest that HOMA-IR contributes to the racial disparities in BC outcomes, particularly for women with HR-positive BCs.

Adherence to adjuvant endocrine therapy among White British and ethnic minority breast cancer survivors in the United Kingdom

OBJECTIVE

Around half of women do not take adjuvant endocrine therapy (AET) as prescribed. Research suggests that adherence rates vary across ethnic groups. This study compared AET adherences rates in White British women and women from minority ethnic groups in the United Kingdom.

METHODS

This is an observational study with 2001 breast cancer survivors recruited from outpatient clinics. Eligible women were diagnosed with primary breast cancer and prescribed AET within the last 3 years. Adherence was measured using the Medication Adherence Rating Scale. Eligible women were asked to complete a questionnaire pack that collected sociodemographic data such as age, relationship status and ethnicity. Independent samples t tests and χ² tests were used to compare White British women and women from minority ethnic groups on self-reported adherence to AET.

RESULTS

Of White British women, 27.8% were classed as non-adherent, compared to 44.4% of women from minority ethnic groups. A logistic regression controlling for relevant demographics indicated that women from minority ethnic groups had a significantly higher risk of non-adherence than women who were White British (odds ratio = 1.50, p = 0.03) CONCLUSION: Rates of non-adherence to AET are higher in women from minority ethnic groups, which may contribute towards racial disparities in breast cancer outcomes. Research with larger and more diverse samples is needed to explore this further and to investigate the psychosocial factors driving differences in adherence.

Breast Cancer in Asia: Incidence, Mortality, Early Detection, Mammography Programs, and Risk-Based Screening Initiatives

Simple Summary

Nearly all breast cancer patients survive for more than five years when the tumor is found early and in the localized stage. Regular clinical breast examinations, mammograms, and monthly self-exams of the breasts all contribute to early detection. However, late-stage breast cancers are common in many Asian countries. Low-income countries suffer from a lack of resources for breast cancer screening. High-income countries, on the other hand, are not benefiting fully from national breast screening programs due to an underutilization of the preventive healthcare services available. Existing reviews on Asian breast cancers are heavily focused on risk factors. The question of whether we should adopt or adapt the knowledge generated from non-Asian breast cancers would benefit from an extension into screening guidelines. In addition, several Asian countries are piloting studies that move away from the age-based screening paradigm.

Abstract

Close to half (45.4%) of the 2.3 million breast cancers (BC) diagnosed in 2020 were from Asia. While the burden of breast cancer has been examined at the level of broad geographic regions, literature on more in-depth coverage of the individual countries and subregions of the Asian continent is lacking. This narrative review examines the breast cancer burden in 47 Asian countries. Breast cancer screening guidelines and risk-based screening initiatives are discussed.

Racial and Ethnic Inequality in Survival Outcomes of Women With Triple Negative Breast Cancer

Purpose

Triple-negative breast cancer (TNBC) is the most lethal group of breast cancers. Socioeconomic factors may contribute to differences in survival rates. This study aims to identify racial/ethnic disparities in five-year survival rates among women affected by TNBC in the United States.

Methods

This retrospective study analyzed data from the 2010-2016 Surveillance, Epidemiology, and End Results Program database. Patients with a primary malignancy of triple-negative breast cancer were included in this study. Cancer-specific survival was measured at five years post-diagnosis. Cox regression models were used to calculate hazard ratios (HR) and corresponding 95% confidence intervals (CI).

Results

From 2010-2016, there were 26,963 women with a primary diagnosis of TNBC. After adjustment for age, insurance, marital status, stage, and surgery type, Hispanic women had the highest hazard of death when compared to White women (adjusted (adj) HR, 1.14, p<0.001). Further, non-Hispanic Black women also had a lower survival probability when compared to White women (adj HR, 1.06, p=0.002).

Conclusion

This study reveals that Hispanic women had the highest hazard of death when compared to White women. As TNBC is the most fatal breast cancer, future studies should investigate socioeconomic factors that may worsen prognosis of this disease.

Surgery Refusal Among Black and Hispanic Women with Non-Metastatic Breast Cancer

BACKGROUND

Studies have shown a lower receipt of treatment among minority women with non-metastatic breast cancer. Those who refuse surgery have increased disease-specific mortality, contributing to disproportionately higher breast cancer mortality in non-Hispanic black (NHB) and Hispanic women. This study aimed to assess surgery refusal in these groups, identify factors associated with surgery refusal, and characterize the association between surgery refusal and survival.

METHODS

Surveillance, Epidemiology, and End Results (SEER) Program data from 2005 to 2015 for NHB and Hispanic women with a diagnosis of non-metastatic breast cancer (n = 113,987) was divided into data of those who underwent surgery and data of those who refused surgery. Sociodemographic and tumor clinical/pathologic differences were analyzed by multivariate logistic regression of predictors of surgery refusal and Cox-proportional hazard model of disease-specific mortality.

RESULTS

Of 799 patients who refused surgery, 562 were NHB and 237 were Hispanic. The percentage of patients refusing surgery increased from 0.6% in 2005 to 0.9% in 2015. The women who refused surgery were more likely to be older than 81 years, less likely to be married, and more likely to be uninsured or have Medicaid. The refusers presented with more advanced disease and more frequent estrogen receptor-positivity (ER+) and progesterone receptor-positivity (PR+) subtype on histology. Breast cancer-specific mortality increased significantly with surgery omission. Surgery refusal was independently associated with NHB race.

CONCLUSION

Surgery refusal among NHB and Hispanic women with potentially curable non-metastatic breast cancer is rising, especially among NHB women, women older than 60 years, single women, and women with a later stage of disease at diagnosis. Additional studies are needed to analyze qualitative data in these populations and their underlying health beliefs, communication needs, and possible use of alternative medicine.

The impact of race and ethnicity in breast cancer-disparities and implications for precision oncology

Breast cancer is the most commonly diagnosed cancer worldwide and is one of the leading causes of cancer death. The incidence, pathological features, and clinical outcomes in breast cancer differ by geographical distribution and across racial and ethnic populations. Importantly, racial and ethnic diversity in breast cancer clinical trials is lacking, with both Blacks and Hispanics underrepresented. In this forum article, breast cancer researchers from across the globe discuss the factors contributing to racial and ethnic breast cancer disparities and highlight specific implications of precision oncology approaches for equitable provision of breast cancer care to improve outcomes and address disparities.