Abstract B12: Racial differences in Androgen Receptor status among triple-negative breast cancers

Abstract

Abstract Background: Triple Negative Breast Cancer (TNBC) is an aggressive subtype of breast cancer with high recurrence and mortality rates. Currently, there are no effective targeted therapies available for TNBC. Emerging data suggest that androgen receptor (AR), a nuclear steroid hormone receptor expressed in 10-43% of TNBCs, has emerged as a promising new biomarker with potential predictive value for certain TNBC subtypes. African American (AA) women suffer from earlier onset of the breast cancer along with significant aggressive disease course when compared to European American (EA) women. This study aimed to determine the prognostic value of AR in a large TNBC cohort and evaluate racewise trends in AR expression status among TNBCs. Methods: We evaluated AR expression immunohistochemically in formalin-fixed paraffin-embedded samples from 822 TNBC patients (142, 95 and 264 patients from Emory, Northside and Grady Memorial Hospitals, respectively, in Atlanta, and 321 from Nottingham Hospital, UK) for whom complete clinicopathologic and overall survival (OS) data were available. Ethnicity data were available for 138 AA and 675 EA TNBC cases. Samples with <1% nuclear-stained cells were considered quadruple-negative (QN). Associations between nuclear AR status, race, other clinicopathologic variables and OS were evaluated through survival analyses and multivariate Cox regression. Results: In this study, 45.6% of the TNBC cases were QN and AAs had a much higher proportion (80.8%) of QN cases than EAs (40.1%, p<0.0001). QN receptor status was significantly associated with younger age (age< 25) at diagnosis, AA ethnicity and higher (KI>14%) proliferative index (p<0.001 for all) in univariate analyses. In multivariate analyses, loss of AR expression was associated with poorer OS (p<0.05, HR=2.8) after adjusting for grade, stage and adjuvant therapy. Conclusion: This study suggest that a higher prevalence of QN breast cancer among AAs may be a plausible reason for the ethnic disparity in outcomes among TNBC patients and strongly support the prognostic role of AR in this breast cancer subtype. Citation Format: Bhattarai Shristi, Jun Xia, Ceyda Sonmez Wetherilt, Sergey Klimov, Ansa Riaz, Sonal Pattni, Mohammad A. Aleskandarany, Andrew R. Green, Emad A. Rakha, Ian O. Ellis, Guilherme Cantuaria, Xiaoxian (Bill) Li, Uma Krishnamurthi, Remus Mihai Osan, Padmashree CG Rida, Ritu Aneja. Racial differences in Androgen Receptor status among triple-negative breast cancers. [abstract]. In: Proceedings of the Ninth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2016 Sep 25-28; Fort Lauderdale, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2017;26(2 Suppl):Abstract nr B12.