Racial Differences in 21-Gene Recurrence Scores Among Patients With Hormone Receptor-Positive, Node-Negative Breast Cancer

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.

Impact of Neighborhood Disadvantage on Tumor Biology and Breast Cancer Survival

OBJECTIVE

The aim of this study was to evaluate the association between neighborhood disadvantage and Oncotype DX score, a surrogate for tumor biology, among a national cohort.

BACKGROUND

Women living in disadvantaged neighborhoods have shorter breast cancer (BC) survival, even after accounting for individual-level, tumor, and treatment characteristics. This suggests unaccounted social and biological mechanisms by which neighborhood disadvantage may impact BC survival.

METHODS

This cross-sectional study included stage I and II, ER + /HER2 - BC patients with Oncotype DX score data from the National Cancer Database (NCDB) from 2004 to 2019. Multivariate regression models tested the association of neighborhood-level income on Oncotype DX score controlling for age, race/ethnicity, insurance, clinical stage, and education. Cox regression assessed overall survival.

RESULTS

Of the 294,283 total BC patients selected, the majority were non-Hispanic White (n=237,197, 80.6%) with 7.6% non-Hispanic Black (n=22,495) and 4.5% other (n=13,383). 27.1% (n=797,254) of the population lived in the disadvantaged neighborhoods with an annual neighborhood-level income of <$48,000, while 59.62% (n=175,305) lived in advantaged neighborhoods with a neighborhood-level income of >$48,000. On multivariable analysis controlling for age, race/ethnicity, insurance status, neighborhood-level education, and pathologic stage, patients in disadvantaged neighborhoods had greater odds of high-risk versus low-risk Oncotype DX scores compared with those in advantaged neighborhoods [odds ratio=1.04 (1.01-1.07), P =0.0067].

CONCLUSION AND RELEVANCE

This study takes a translational epidemiologic approach to identify that women living in the most disadvantaged neighborhoods have more aggressive tumor biology, as determined by the Oncotype DX score.

Differential distribution of actual and surrogate oncotype DX recurrence scores in breast cancer patients by age, menopausal status, race, and body mass index

PURPOSE

The Oncotype DX Recurrence Score (RS) is a widely used prognostic tool for estrogen receptor-positive breast cancer patients. Multiple surrogate models can predict RS with good accuracy. In this study we aimed to determine whether the RS and two surrogate indices were differentially distributed by age, menopausal status, race, and body mass index (BMI).

METHODS

516 breast cancer cases treated at a single institution were analyzed. Epidemiologic data, RS, tumor size, grade, and biomarker data were abstracted. Breast Cancer Prognostic Score (BCPS) and modified Magee equation 2 were used to calculate surrogate RS. Patients were stratified into different groups based on age, menopausal status, race, BMI, or a combination of strata. Mean and standard deviation were calculated for each group/subgroup.

RESULTS

Age below median (< 63) was associated with higher RS, especially in obese and Black patients. RS was also higher in obese and Black patients in the premenopausal subgroup. Black patients had a higher RS compared to White women in the premenopausal and non-obese subgroups. BMI < 30 was associated with higher RS, especially in older, postmenopausal, and Black patients. Some of these observations were replicated by the two surrogate models. The surrogate recurrence scores were higher in the younger age group, in non-obese older/postmenopausal women, and in younger/premenopausal obese individuals.

CONCLUSIONS

Higher RS was observed in younger and premenopausal breast cancer patients, especially among the Black and obese subgroups, and in non-obese patients, especially among Black and older/postmenopausal women, suggesting more aggressive disease in these subgroups. Some statistical differences could be replicated by both surrogate models, suggesting that they may have utility in breast cancer epidemiology studies that do not have access to Oncotype DX RS or patient outcome data.

Predictive value of machine learning for breast cancer recurrence: a systematic review and meta-analysis

PURPOSE

Recurrence of breast cancer leads to a high lifetime risk and a low 5 year survival rate. Researchers have used machine learning to predict the risk of recurrence in patients with breast cancer, but the predictive performance of machine learning remains controversial. Hence, this study aimed to explore the accuracy of machine learning in predicting breast cancer recurrence risk and aggregate predictive variables to provide guidance for the development of subsequent risk scoring systems.

METHODS

We searched Pubmed, EMBASE, Cochrane, and Web of Science. The risk of bias in the included studies was evaluated using prediction model risk of bias assessment tool (PROBAST). Meta-regression was adopted to explore whether there was a significant difference in the recurrence time by machine learning.

RESULTS

Thirty-four studies involving 67,560 subjects were included, among whom 8695 experienced breast cancer recurrence. The c-index of prediction models was 0.814 (95%CI 0.802-0.826) and 0.770 (95%CI 0.737-0.803) in the training and validation sets, respectively; the sensitivity and specificity were 0.69 (95% CI 0.64-0.74), 0.89 (95% CI 0.86-0.92) in the training, and 0.64 (95% CI 0.58-0.70), 0.88 (95% CI 0.82-0.92) in the validation, respectively. Age, histological grading, and lymph node status are the most commonly used variables in model construction. Attention should be paid to unhealthy lifestyles such as drinking, smoking and BMI as modeling variables. Risk prediction models based on machine learning have long-term monitoring value for breast cancer population, and subsequent studies should consider using large-sample and multi-center data to establish risk equations for verification.

CONCLUSION

Machine learning may be used as a predictive tool for breast cancer recurrence. Currently, there is a lack of effective and universally applicable machine learning models in clinical practice. We expect to incorporate multi-center studies in the future and attempt to develop tools for predicting breast cancer recurrence risk, so as to effectively identify populations at high risk of recurrence and develop personalized follow-up strategies and prognostic interventions to reduce the risk of recurrence.

Association of Social Determinants and Tumor Biology With Racial Disparity in Survival From Early-Stage, Hormone-Dependent Breast Cancer

Importance

Black women with hormone receptor-positive breast cancer experience the greatest racial disparity in survival of all breast cancer subtypes. The relative contributions of social determinants of health and tumor biology to this disparity are uncertain.

Objective

To determine the proportion of the Black-White disparity in breast cancer survival from estrogen receptor (ER)-positive, axillary node-negative breast cancer that is associated with adverse social determinants and high-risk tumor biology.

Design, Setting, and Participants

A retrospective mediation analysis of factors associated with the racial disparity in breast cancer death for cases diagnosed between 2004 and 2015 with follow-up through 2016 was carried out using the Surveillance, Epidemiology, and End Results (SEER) Oncotype registry. The study included women in the SEER-18 registry who were aged 18 years or older at diagnosis of a first primary invasive breast cancer tumor that was axillary node-negative and ER-positive, who were Black (Black), non-Hispanic White (White), and for whom the 21-gene breast recurrence score was available. Data analysis took place between March 4, 2021, and November 15, 2022.

Exposures

Census tract socioeconomic disadvantage, insurance status, tumor characteristics including the recurrence score, and treatment variables.

Main Outcomes and Measures

Death due to breast cancer.

Results

The analysis with 60 137 women (mean [IQR] age 58.1 [50-66] years) included 5648 (9.4%) Black women and 54 489 (90.6%) White women. With a median (IQR) follow-up time of 56 (32-86) months, the age-adjusted hazard ratio (HR) for breast cancer death among Black compared with White women was 1.82 (95% CI, 1.51-2.20). Neighborhood disadvantage and insurance status together mediated 19% of the disparity (mediated HR, 1.62; 95% CI, 1.31-2.00; P < .001) and tumor biological characteristics mediated 20% (mediated HR, 1.56; 95% CI, 1.28-1.90; P < .001). A fully adjusted model that included all covariates accounted for 44% of the racial disparity (mediated HR, 1.38; 95% CI, 1.11-1.71; P < .001). Neighborhood disadvantage mediated 8% of the racial difference in the probability of a high-risk recurrence score (P = .02).

Conclusions and Relevance

In this study, racial differences in social determinants of health and indicators of aggressive tumor biology including a genomic biomarker were equally associated with the survival disparity in early-stage, ER-positive breast cancer among US women. Future research should examine more comprehensive measures of socioecological disadvantage, molecular mechanisms underlying aggressive tumor biology among Black women, and the role of ancestry-related genetic variants.

Fibroblasts as Turned Agents in Cancer Progression

Differentiated epithelial cells reside in the homeostatic microenvironment of the native organ stroma. The stroma supports their normal function, their G0 differentiated state, and their expansion/contraction through the various stages of the life cycle and physiologic functions of the host. When malignant transformation begins, the microenvironment tries to suppress and eliminate the transformed cells, while cancer cells, in turn, try to resist these suppressive efforts. The tumor microenvironment encompasses a large variety of cell types recruited by the tumor to perform different functions, among which fibroblasts are the most abundant. The dynamics of the mutual relationship change as the sides undertake an epic battle for control of the other. In the process, the cancer “wounds” the microenvironment through a variety of mechanisms and attracts distant mesenchymal stem cells to change their function from one attempting to suppress the cancer, to one that supports its growth, survival, and metastasis. Analogous reciprocal interactions occur as well between disseminated cancer cells and the metastatic microenvironment, where the microenvironment attempts to eliminate cancer cells or suppress their proliferation. However, the altered microenvironmental cells acquire novel characteristics that support malignant progression. Investigations have attempted to use these traits as targets of novel therapeutic approaches.

Oncotype DX Risk Recurrence Score and Total Mortality for Early-Stage Breast Cancer by Race/Ethnicity

BACKGROUND

Oncotype DX recurrence score (ODX RS) is a prognostic biomarker for early-stage, node-negative, estrogen receptor-positive (ER+) breast cancer. Whether test uptake, associated factors, and the test's prognostic values differ by race/ethnicity is unknown.

METHODS

From the National Cancer Database, 2010-2014, we identified 227,259 early-stage ER+, node-negative breast cancer cases. Logistic regression was used to examine ODX RS uptake and associated factors among non-Hispanic White (White), non-Hispanic Black (Black), Hispanic, and Asian American patients. Cox regression was used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for overall mortality with ODX RS by race/ethnicity.

RESULTS

White patients were more likely to receive an ODX RS test compared with Black, Hispanic, and Asian American patients (36.7%, 32.8%, 31.6%, and 35.5%, respectively; P < 0.001). Disparities persisted after adjustments for demographics, clinical characteristics, and access-to-care, with rate ratios of 0.87 (95% CI, 0.85-0.88), 0.82 (95% CI, 0.80-0.85), and 0.89 (95% CI, 0.87-0.92), respectively, for Black, Hispanic, and Asian American compared with White patients. Black patients had higher proportions of high-risk scores (≥26) compared with White, Hispanic, and Asian American patients (19.1%, 14.0%, 14.2%, and 15.6%, respectively; P < 0.0001). ODX RS was predictive for total mortality across all races/ethnicities, particularly younger patients (<50). No significant race/ethnicity interactions were observed.

CONCLUSIONS

Although ODX RS uptake and risk distribution varied by race/ethnicity, ODX RS was prognostic for mortality across groups.

IMPACT

These findings emphasize the importance of developing strategies to increase ODX RS uptake among racial/ethnic minorities and call for more investigations on potential racial/ethnic differences in breast cancer biology. See related commentary by Wang et al., p. 704.

Racial/Ethnic Differences and Trends in Pathologic Complete Response Following Neoadjuvant Chemotherapy for Breast Cancer

Simple Summary

Despite improving rates of pathologic complete response (pCR; the absence of invasive cancer at the time of surgery) among patients with breast cancer who underwent chemotherapy prior to surgery, racial and ethnic minority groups were under-represented in clinical trials. Our study used a large cancer registry database in the United States to evaluate the temporal trend of pCR and patterns of pCR and survival outcomes among diverse racial and ethnic groups. It suggested that although pCR rates improved over time for all groups, pCR rates and survival outcomes varied significantly. For instance, compared to non-Hispanic White women, Black women were less likely to have pCR for triple negative and hormone receptor (HR)-negative, human epidermal growth factor receptor 2 (HER2)-positive tumors, but more likely for HR-positive, HER2-negative tumors. Given such heterogeneous outcomes among various racial and ethnic minority groups, further investigations would be warranted to optimize outcomes among such underserved populations.

Abstract

The purpose of this study was to evaluate nationwide trends in pathologic complete response (pCR) and its racial variations for breast cancer. The National Cancer Database was queried for women from 2010 to 2017 with non-metastatic breast cancer who underwent neoadjuvant chemotherapy. The primary endpoints, pCR and overall survival, were evaluated using Cochran-Armitage test, logistic, and Cox regression multivariable analyses. A total of 104,161 women were analyzed. Overall, pCR improved from 2010 to 2017 (15.1% to 27.2%, trend p < 0.001). Compared to non-Hispanic White (NHW) women, Hispanic White (HW) women were more likely to have pCR for hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-positive tumors (adjusted odds ratio (aOR) 1.29, 95% confidence interval (CI) 1.08–1.53, p = 0.005). Black women were less likely to have pCR for HR-HER2+ tumors (aOR 0.81, 95% CI 0.73–0.89, p < 0.001) and triple negative (aOR 0.82, 95% CI 0.77–0.87, p < 0.001) tumors, but more likely for HR+HER2- tumors (aOR 1.13, 95% CI 1.03–1.24, p = 0.009). Among patients who achieved pCR, Asian or Pacific Islander (API) women were associated with better survival (adjusted hazards ratio (aHR) 0.52, 95% CI 0.33–0.82, p = 0.005) than NHW women. Despite positive trends in pCR rates, the likelihood of pCR and survival outcomes may be intricately dependent on racial/ethnic groups and tumor receptor subtypes.

Adherence to Endocrine Therapy and Racial Outcome Disparities in Breast Cancer

The disparity in outcomes of breast cancer for Black compared with White women in the U.S. is well known and persistent over time, with the largest disparities appearing among women with hormone receptor-positive (HR+) cancers. The racial gap in breast cancer survival first emerged in the 1980s, a time of significantmen treatment advances in early-stage breast cancer, including the introduction of adjuvant endocrine therapy. Since that time, the gap has continued to widen despite steady advances in treatment and survival of breast cancer overall. Although advanced stage at presentation and unfavorable biology undoubtedly contribute to racial differences in survival of HR+ breast, treatment disparities are increasingly acknowledged to play a key role as well. The recent recognition of racial differences in endocrine therapy use may be a key explanatory factor in the persistent racial gap in mortality of HR+ disease, and may be a key focus of intervention to improve breast cancer outcomes for Black women. IMPLICATIONS FOR PRACTICE: Black women with hormone receptor-positive breast cancer experience the greatest racial disparity in survival among all breast cancer subtypes. This survival gap appears consistently across studies and is not entirely explained by differences in presenting stage, tumor biology as assessed by genomic risk scores, or receipt of chemotherapy. Recent research highlights lower adherence to endocrine therapy (ET) for Black women. Health systems and individual providers should focus on improving communication about the importance of ET use, sharing decisions around ET, providing appropriate support for side effects and other ET-related concerns, and equitably delivering survivorship care, including ET adherence assessment.

Risk evaluation of early-stage hormone receptor-positive and human epidermal growth factor receptor 2-negative breast cancer patients: a population-based study from Taiwan

PURPOSE

To assess the prognostic value of the Dutch criteria for patients with early-stage hormone receptor-positive and human epidermal growth factor receptor 2-negative breast cancer from the Taiwan Cancer Registry Database.

PATIENTS AND METHODS

We included 8295 patients with early-stage node-negative breast cancer who underwent surgery during January 2008-December 2012. Patients were stratified into low- and high-risk groups based on the Dutch criteria. The Kaplan-Meier method and log-rank test were used to estimate the difference in breast cancer-specific survival (BCSS) and overall survival (OS) between groups. Multivariable analysis was used to evaluate the prognostic value of the Dutch criteria.

RESULTS

Overall, the low-risk and high-risk groups comprised 5375 and 2920 patients, respectively. In the low- and high-risk groups, the 5-year BCSS rate was 99.6% and 98.2% (P < 0.0001) and the 5-year OS rate was 98.3% and 96.8% (P < 0.0001), respectively. The hazard ratio for BCSS was 4.18 (95% confidence interval [CI] 2.63-6.63, P < 0.0001), and the hazard ratio for OS was 1.94 (95% CI 1.48-2.55); both were significantly poorer in the high-risk group than in the low-risk group. In the low-risk group, the 5-year BCSS and OS of patients who did and did not receive adjuvant chemotherapy were similar (99.5% versus 99.6% [P = 0.927] and 98.8% and 98.1% [P = 0.0683], respectively).

CONCLUSION

The prognosis of low-risk patients as classified using the Dutch criteria is excellent with or without adjuvant chemotherapy. The benefit of multi-gene testing for chemotherapy decision-making might be minimal in these patients.

A Review of Research on Disparities in the Care of Black and White Patients With Cancer in Detroit

Racial disparities in cancer incidence and outcomes are well-documented in the US, with Black people having higher incidence rates and worse outcomes than White people. In this review, we present a summary of almost 30 years of research conducted by investigators at the Karmanos Cancer Institute's (KCI's) Population Studies and Disparities Research (PSDR) Program focusing on Black-White disparities in cancer incidence, care, and outcomes. The studies in the review focus on individuals diagnosed with cancer from the Detroit Metropolitan area, but also includes individuals included in national databases. Using an organizational framework of three generations of studies on racial disparities, this review describes racial disparities by primary cancer site, disparities associated with the presence or absence of comorbid medical conditions, disparities in treatment, and disparities in physician-patient communication, all of which contribute to poorer outcomes for Black cancer patients. While socio-demographic and clinical differences account for some of the noted disparities, further work is needed to unravel the influence of systemic effects of racism against Black people, which is argued to be the major contributor to disparate outcomes between Black and White patients with cancer. This review highlights evidence-based strategies that have the potential to help mitigate disparities, improve care for vulnerable populations, and build an equitable healthcare system. Lessons learned can also inform a more equitable response to other health conditions and crises.

Trends in Breast Cancer Survival by Race-Ethnicity in Florida, 1990-2015

BACKGROUND

This study was conducted to evaluate trends in survival, by race-ethnicity, for women diagnosed with breast cancer in Florida over a 26-year period.

METHODS

This was a retrospective cohort study of women diagnosed with invasive breast cancer in Florida between 1990 and 2015. Data were obtained from the Florida Cancer Data System. Women in the study were categorized according to race (white/black) and Hispanic ethnicity (yes/no). Cumulative incidence estimates of 5- and 10-year breast cancer-related death with 95% confidence intervals (CI) were obtained by race-ethnicity, according to diagnosis year. Subdistribution hazard models were used to obtain subdistribution HRs (sHR) for the relative rate of breast cancer death accounting for competing causes.

RESULTS

Breast cancer mortality decreased for all racial-ethnic groups, and racial-ethnic minorities had greater absolute and relative improvement for nearly all metrics compared with non-Hispanic white (NHW) women. However, for the most recent time period (2010-2015), black women still experienced significant survival disparities with non-Hispanic black (NHB) women, having twice the rate of 5-year [sHR = 2.04; 95% confidence interval (CI), 1.91-2.19] and 10-year (sHR = 2.02; 95% CI, 1.89-2.16) breast cancer-related death. Adjustment for covariates substantially reduced the excess rate of breast cancer-related death for black women.

CONCLUSIONS

Despite efforts to improve disparities in breast cancer outcomes for underserved women in Florida, black women continue to experience significant survival disparities.

IMPACT

These results highlight the need for targeted approaches to eliminate disparities in breast cancer survival for black women.

Association of Race/Ethnicity and the 21-Gene Recurrence Score With Breast Cancer-Specific Mortality Among US Women

Importance

Given the widespread use of the 21-gene recurrence score for identifying candidates for adjuvant chemotherapy, it is important to examine the performance of the Oncotype DX Breast Recurrence Score test in diverse patient populations to validate this approach for tailoring treatment in women in racial/ethnic minority groups.

Objective

To examine whether breast cancer-specific mortality for women with hormone-dependent breast cancer differs by race/ethnicity across risk categories defined by the Oncotype DX Breast Recurrence Score test and whether the prognostic accuracy of the 21-gene recurrence score differs by race/ethnicity.

Design, Setting, and Participants

This retrospective, population-based cohort study used the Surveillance, Epidemiology, and End Results Oncotype DX 2004-2015 database to obtain breast cancer-specific survival data on US women 18 years and older who were diagnosed with first primary stage I to III, estrogen receptor-positive breast cancer between January 1, 2004, and December 31, 2015, and had tumor testing through the Genomic Health Clinical Laboratory. Data were analyzed from April 20 to September 27, 2020.

Main Outcomes and Measures

The primary outcome was breast cancer-specific mortality among women from different racial/ethnic groups stratified by the 21-gene recurrence score risk categories. Secondary analyses compared the prognostic accuracy of the recurrence score among the different racial/ethnic groups.

Results

A total of 86 033 patients with breast cancer (mean [SD] age, 57.6 [10.6] years) with Oncotype DX Breast Recurrence Score test information were available for the analysis, including 64 069 non-Hispanic White women (74.4%), 6719 non-Hispanic Black women (7.8%), 7944 Hispanic women (9.2%), 6950 Asian/Pacific Islander women (8.0%), and 351 American Indian/Alaska Native women (0.4%). Black women were significantly more likely than non-Hispanic White women to have a recurrence score greater than 25 (17.7% vs 13.7%; P < .001). Among women with axillary node-negative tumors, competing risk models adjusted for age, tumor characteristics, and treatment found higher breast cancer-specific mortality for Black compared with non-Hispanic White women within each recurrence score risk stratum, with subdistribution hazard ratios of 2.54 (95% CI, 1.44-4.50) for Black women with recurrence scores of 0 to 10, 1.64 (95% CI, 1.23-2.18) for Black women with recurrence scores of 11 to 25, and 1.48 (95% CI, 1.10-1.98) for Black women with scores greater than 25. The prognostic accuracy of the recurrence score was significantly lower for Black women, with a C index of 0.656 (95% CI, 0.592-0.720) compared with 0.700 (95% CI, 0.677-0.722) (P = .002) for non-Hispanic Whites.

Conclusions and Relevance

In this cohort study, Black women in the US were more likely to have a high-risk recurrence score and to die of axillary node-negative breast cancer compared with non-Hispanic White women with comparable recurrence scores. The Oncotype DX Breast Recurrence Score test has lower prognostic accuracy in Black women, suggesting that genomic assays used to identify candidates for adjuvant chemotherapy may require model calibration in populations with greater racial/ethnic diversity.

Racial and ethnic disparities in 21-gene recurrence scores, chemotherapy, and survival among women with hormone receptor-positive, node-negative breast cancer

PURPOSE

Cutoffs of the 21-gene recurrence score (RS), a commonly used genomic assay for hormone receptor-positive breast cancer, have been updated. Little is known about racial/ethnic differences in RS results, RS-guided chemotherapy use, and outcomes on updated cutoff (RS ≥ 31 defined as high-risk) in the real-world setting.

METHODS

A total of 81,937 women [75.0% whites, 7.7% blacks, 8.3% Asian American/Pacific Islanders (AAPIs), and 9.0% Hispanics] diagnosed with hormone receptor-positive breast cancer between 2004 and 2015, who received the 21-gene assay, were identified from the Surveillance, Epidemiology, and End Results. Logistic regressions estimated the race-associated odds ratios (ORs) of RS and chemotherapy use. Cox regressions estimated the race-associated hazard ratios (HRs) of breast cancer-specific and all-cause mortality.

RESULTS

Compared with white women, black women were more likely to have RS-defined high-risk tumors (adjusted OR [aOR] 1.29; 95% CI 1.16-1.42). In high RS, blacks had lower odds of chemotherapy use (aOR 0.76; 95% CI 0.62-0.94) than whites, particularly among women ≥ 65 years (aOR 0.51; 95% CI 0.35-0.76), while AAPI and Hispanic women had no variation in chemotherapy use compared with whites in high RS. Black women had a higher risk of breast cancer-specific mortality (HR 1.37; 95% CI 1.12-1.67) and all-cause mortality compared with white women after adjusting for demographic and pathological factors, county-level socioeconomic deprivation, treatments and RS; AAPIs had lower mortality and Hispanics had similar mortality.

CONCLUSIONS

Black women were more likely to have a high-risk RS tumor and less likely to receive chemotherapy in the group of high RS, especially those ≥ 65 years. Further studies are needed to identify barriers to chemotherapy in black patients with high RS scores.

Racial differences in estrogen receptor staining levels and implications for treatment and survival among estrogen receptor positive, HER2-negative invasive breast cancers

BACKGROUND

African American women (AAW) die more frequently from estrogen receptor (ER) positive breast cancer than European American women (EAW). We investigated the relationship between race, percent ER staining, treatment, and clinical outcomes.

METHODS

Percent ER staining (weakly ER+: 1-10%, moderately ER+: 11-50%, strongly ER+: > 50%) was abstracted from pathology reports for 1573 women with ER+/HER2- invasive breast cancer treated at a single cancer center in Detroit, MI from 2010 to 2017. Clinical outcomes and tumor characteristics were obtained from the Metropolitan Detroit Cancer Surveillance System. Associations of ER levels with demographic and clinical characteristics were evaluated using logistic regression. Overall and breast cancer-specific (BCS) survival were evaluated using Cox proportional hazards models.

RESULTS

AAW were more likely to have tumors with lower ER staining levels than EAW (weakly ER+: Odds ratio (OR) 2.19, p = 0.019; moderately ER+: OR 2.80, p = 0.005). Women with weakly compared to strongly ER+ tumors were less likely to receive endocrine therapy (ET) regardless of race (OR 0.79, p < 0.001). Mortality was predicted by both AA race (Overall hazard ratio (HR) = 1.72, p < 0.001; BCS HR 1.45, p = 0.08) and low (1-50%) ER (Overall HR 1.57, p = 0.083; BCS HR 2.11, p = 0.017) adjusting for clinic-pathologic characteristics. ET was associated with improved BCS survival in all women (1-50%: HR 0.11, p < 0.001; > 50%: HR 0.24, p < 0.001).

CONCLUSION

The biology of ER+/HER2- tumors varies by race, although this does not appear to account for racial differences in survival. Although ET substantially reduces mortality among women with weakly ER+ tumors, these women are less likely to be treated with ET and have poorer outcomes.

Racial Differences in the Association Between Luminal Master Regulator Gene Expression Levels and Breast Cancer Survival

PURPOSE

Compared with their European American (EA) counterparts, African American (AA) women are more likely to die from breast cancer in the United States. This disparity is greatest in hormone receptor-positive subtypes. Here we uncover biological factors underlying this disparity by comparing functional expression and prognostic significance of master transcriptional regulators of luminal differentiation.

EXPERIMENTAL DESIGN

Data and biospecimens from 262 AA and 293 EA patients diagnosed with breast cancer from 2001 to 2010 at a major medical center were analyzed by IHC for functional biomarkers of luminal differentiation, including estrogen receptor (ESR1) and its pioneer factors, FOXA1 and GATA3. Integrated comparison of protein levels with network-level gene expression analysis uncovered predictive correlations with race and survival.

RESULTS

Univariate or multivariate HRs for overall survival, estimated from digital IHC scoring of nuclear antigen, show distinct differences in the magnitude and significance of these biomarkers to predict survival based on race: ESR1 [EA HR = 0.47; 95% confidence interval (CI), 0.31-0.72 and AA HR = 0.77; 95% CI, 0.48-1.18]; FOXA1 (EA HR = 0.38; 95% CI, 0.23-0.63 and AA HR = 0.53; 95% CI, 0.31-0.88), and GATA3 (EA HR = 0.36; 95% CI, 0.23-0.56; AA HR = 0.57; CI, 0.56-1.4). In addition, we identify genes in the downstream regulons of these biomarkers highly correlated with race and survival.

CONCLUSIONS

Even within clinically homogeneous tumor groups, regulatory networks that drive mammary luminal differentiation reveal race-specific differences in their association with clinical outcome. Understanding these biomarkers and their downstream regulons will elucidate the intrinsic mechanisms that drive racial disparities in breast cancer survival.

BCT score predicts chemotherapy benefit in Asian patients with hormone receptor-positive, HER2-negative, lymph node-negative breast cancer

The Breast Cancer Test (BCT) score has been validated for its ability to predict the risk of distant metastasis in hormone receptor-positive, human epidermal growth factor receptor 2 (HER2)-negative early breast cancer. This study aimed to examine the value of the BCT score for predicting the benefit of adjuvant chemotherapy for Korean women with hormone receptor-positive, HER2-negative, lymph node-negative breast cancer. The study included 346 patients treated with either hormone therapy alone (n = 203) or hormone therapy plus chemotherapy (n = 143), and compared patient survival between the two treatment groups. The effect of BCT score on patient survival by treatment group was assessed using Cox proportional hazards models. Based on the results, the BCT score was prognostic for distant metastasis-free survival and breast cancer-specific survival in the hormone therapy alone group. There was no significant difference between the treatment groups in terms of 10-year distant metastasis-free survival in the overall patient population. However, when patients were classified as low risk (n = 266) and high risk (n = 80) according to the BCT score, addition of adjuvant chemotherapy to hormone therapy for patients classified as BCT high-risk group led to a significant improvement in 10-year distant metastasis-free survival, from 65.4% to 91.9% (hazard ratio, 0.18; 95% confidence interval, 0.05–0.64; P = 0.003); in contrast, there was no benefit for the BCT low-risk group. The stratification of patients according to the BCT score also identified clinically high-risk patients who may not benefit from chemotherapy. Results were similar for breast cancer-specific survival. In conclusion, the BCT score was not only of prognostic value but was also a predictor of chemotherapy benefit for Korean patients with hormone receptor-positive, HER2-negative, lymph node-negative breast cancer.