Table 1.

Studies Reporting Luminal Breast Cancer Survival and Clinical Outcomes Among African American and European American Patients

References	Title	Project goal	Key findings
Rauscher et al [9]	Racial disparity in survival from estrogen and progesterone receptor positive breast cancer: implications for reducing breast cancer mortality disparities	To elucidate factors contributing to survival disparity observed among AA women with luminal breast cancer	• The observed racial disparity in luminal breast cancer survival did not appear to be due to differences in tumor stage, grade or therapy initiation.
Collin, et al [94]	Racial Disparities in Breast Cancer Outcomes in the Metropolitan Atlanta Area: New Insights and Approaches for Health Equity	To evaluate racial disparities in breast cancer outcomes among patients residing in the Atlanta metro area	• The largest disparities in breast cancer survival between AA with EA patients were found with those diagnosed with luminal breast cancer. • Interestingly, these disparities were more pronounced among women of high social economic status.
Huo, et al [95]	Comparison of Breast Cancer Molecular Features and Survival by African and European Ancestry in The Cancer Genome Atlas	To compare breast cancer molecular features and survival in tumors among AA and EA patients using TCGA	• Overall AA breast cancer patients had a higher mortality rate with the breast cancer free interval differences greatest among those with basal like tumors. • However, tumors from AA luminal breast cancer patients were found to exhibit risk of relapse scores that were statistically higher than that of EA patients.
Troester, et al [96]	Racial Differences in PAM50 Subtypes in the Carolina Breast Cancer Study	To evaluate racial differences in the relative frequency of molecular subtypes and tumor biology and assesses whether differences in tumor genomics persist even within clinically defined subgroups	• Black women of all ages had a statistically significantly lower frequency of luminal A breast cancer. • All other subtype frequencies were higher in Black women. Among clinically HR+/HER2- cases, Risk of Recurrence (ROR) scores were statistically significantly higher among Black women.
O’Brien, et al [97]	Intrinsic Breast Tumor Subtypes, Race, and Long-Term Survival in the Carolina Breast Cancer Study	To identify differences in breast cancer-specific mortality across four “intrinsic” tumor subtypes: luminal A, luminal B, basal-like, and human epidermal growth factor receptor 2 positive/estrogen receptor negative (HER2+/ER−) in AA women	• Breast cancer mortality was higher for participants with HER2+/ERand basal-like breast cancer compared with luminal A and B. • African Americans had higher breast cancer-specific mortality than whites, but the effect of race was statistically significant only among women with luminal A breast cancer.
Farias, et al [105]	Racial differences in long-term adjuvant endocrine therapy adherence and mortality among Medicaid-insured breast cancer patients in Texas: Findings from TCR-Medicaid linked data	To determine racial differences in the adherence to ET and mortality among Medicaid patients in TX	• Long-term adherence is suboptimal particularly among AA patients on Medicaid. • AA women were less likely to use adjuvant ET and more likely to discontinue therapy as compared to EA women. • Discontinuation was associated with higher risk of all-cause and cancer-specific mortality irrespective of hormone receptor status.
Reeder-Hayes, et al [106]	Racial Disparities in Initiation of Adjuvant Endocrine Therapy of Early Breast Cancer	To determine whether racial disparities exist in therapy initiation	• AA women were less likely to initiate ET than EA women and more likely to undergo chemotherapy. This represents an important contributor to the racial survival disparity.
Tichy, et al [107]	Race, Response to Chemotherapy, and Outcome Within Clinical Breast Cancer Subtypes	To identify racial differences in response to chemotherapeutic response and long-term survival among breast cancer patients	• Black women had worse time to recurrence though there was no significant difference in overall survival. • Black women with ER+ breast experienced worse outcomes though relative sensitivity to chemotherapy appeared not to play a role.
Purrington et al. [108]	Racial differences in estrogen receptor staining levels and implications for treatment and survival among estrogen receptor positive, HER2-negative invasive breast cancers	To determine the relationship between race, percent ER staining, treatment, and clinical outcomes	• AA women are more likely to have tumors with weak ER stain than EA women. • Women with tumors found to weakly stain for ER are less likely to receive ET irrespective of race. • Increased mortality is associated with AA race and weak ER tumor staining.
Byun et al [109]	Racial Differences in the Association Between Luminal Master Regulator Gene Expression Levels and Breast Cancer Survival	To uncover biological factors underlying the racial breast cancer survival disparity by comparing functional expression and prognostic significance of master transcriptional regulators of luminal differentiation.	• Luminal master regulatory genes ESRI, FOXA1 and GATA3 show significant differential expression based on race which correlates with survival. • Downstream regulons to these genes also correlated highly with race and survival.

Abbreviations: TCR, Texas Cancer Registry; AA, African American; EA, European American; ER, estrogen receptor; TN, triple negative; AET, adjuvant endocrine therapy; HER, human epidermal growth factor receptor; ET, endocrine therapy.