Impact of molecular subtype and race on HR+, HER2- breast cancer survival.

PURPOSE: There is an urgent need to understand the biological factors contributing to the racial survival disparity among women with hormone receptor-positive (HR+), HER2- breast cancer. In this study, we examined the impact of PAM50 subtype on 10-year mortality rate in women with HR+, HER2- breast cancer by race. METHODS: Women with localized, HR+, HER2- breast cancer diagnosed between 2002 and 2012 from two population-based cohorts were evaluated. Archival tumors were obtained and classified by PAM50 into four molecular subtypes (i.e., luminal A, luminal B, HER2-enriched, and basal-like). The molecular subtypes within HR+, HER2- breast cancers and corresponding 10-year mortality rate were compared between Black and Non-Hispanic White (NHW) women using Cox proportional hazard ratios and survival analysis, adjusting for covariates. RESULTS: In this study, 318 women with localized, HR+, HER2- breast cancer were included-227 Black (71%) and 91 NHW (29%). Young Black women (age ≤ 50) had the highest proportion of HR+, non-luminal A tumors (47%), compared to young NHW (10%), older Black women (31%), and older NHW (30%). Overall, women with HR+, non-luminal A subtypes had a higher 10-year mortality rate compared to HR+, luminal A subtypes after adjustment for age, stage, and income (HR 4.21 for Blacks, 95% CI 1.74-10.18 and HR 3.44 for NHW, 95% CI 1.31-9.03). Among HR+, non-luminal A subtypes there was, however, no significant racial difference in 10-yr mortality observed (Black vs. NHW: HR 1.23, 95% CI 0.58-2.58). CONCLUSION: Molecular subtype classification highlights racial disparities in PAM50 subtype distribution among women with HR+, HER2- breast cancer. Among women with HR+, HER2- breast cancer, racial survival disparities are ameliorated after adjusting for molecular subtype.

Disparities in Genetic Testing and Care among Black women with Hereditary Breast Cancer.

PURPOSE OF REVIEW: Despite a steady improvement in breast cancer survival rates over the past several decades, mortality disparities remain among Black women, who have a 42% higher death rate compared to non-Hispanic white (NHW) women. Hereditary breast cancer (HBC) accounts for 5-10% of all breast cancer cases, the majority of which are due to the BRCA1 and BRCA2 (BRCA) genes. Despite the availability of BRCA testing for over 25 years, there remain disproportionately lower rates of genetic testing among Blacks compared to NHW due to a multitude of factors. The intent of this review is to discuss racial disparities focused on HBC across diverse populations and review the existing gaps to be addressed when delivering gene-based care. RECENT FINDINGS: The factors contributing to the racial survival disparity are undoubtedly complex and likely an interplay between tumor biology, genomics, patterns of care and socioeconomic factors. Advances in genomic technologies that now allow for full characterization of germline DNA sequencing are integral in defining the complex and multifactorial cause of breast cancer and may help to explain the existing racial survival disparities. SUMMARY: Identification of inherited cancer risk may lead to cancer prevention, early cancer detection, treatment guidance, and ultimately has great potential to improve outcomes. Consequently, advances in HBC diagnosis and treatment without widespread implementation have the potential to further widen the existing breast cancer mortality gap between Black and NHW women.