Abstract A96: Breast tumor subtypes and survival outcomes in African American and Latina patients in South Los Angeles

Abstract

Abstract Background: Recent studies have shown that minority women, in particular African American are more likely to express Triple Negative (TN) tumors compared to Non-Hispanic Whites. TN tumors are more difficult to treat this may be one of the factors contributing to disparities in disease outcome and overall survival. In our study, we have studied a cohort of African American and Latina women with equal socio-economic status (SES) and access to care. The purpose of this study was to determine if these two ethnic groups with equal SES and access to care had differences in disease outcome and if this difference was related to tumor subtypes. We have also examined cellular and molecular markers associated with tumor subtypes and disease outcome. Methods: A total of 300 subjects were retrospectively selected. 156 were African American and 144 Latina. Demographic, pathologic, and clinical follow-up information were collected from existing database. The prevalence of breast cancer subtypes within racial and menopausal subsets was examined and the associations with tumor size, lymph nodal status, staging, and histologic grade were determined by logistic regression. Disease-free survival (DFS) was analyzed by Kaplan-Meier survival curves with log-rank test. Gene and protein signatures associated with PI3kinase/Akt and the CD44/CD24 expression profiles were analyzed by immunohistochemistry analysis (IHC) in different tumor subtypes. Results: The TN or basal-like breast cancer subtype (ER/PR/HER2 negative) was more prevalent among premenopausal African American women (36%) compared to postmenopausal African Americans (28.1); premenopausal Latina women (31 %); and postmenopausal Latinas (17%) (p=0.05). The HER2+/ER-subtype was more prevalent among premenopausal Latina women (17%) than postmenopausal Latinas (14%), postmenopausal African American women (9%), and premenopausal African American women (3%) (p=0.046). Prevalence of Luminal A and Luminal B breast cancer subtypes were similar with race and menopausal status. Compared to Luminal A, basal-like tumors were more poorly differentiated (OR=6.4, p<0.001) and more likely to have CD44+/CD24-phenotype, while HER2+/ER-tumors were more associated with large tumor size (OR=3.1, p=0.01) and CD24+ phenotype. The Luminal B tumors were also more likely to be associated with larger tumor size and were poorly differentiated (OR=3.0, p=0.002). Patients with basal-like and HER2+/ER-tumors had significant shorter DFS compared to patients with Luminal A tumors (log rank=11.97, p=0.0005 and log rank=8.95, p=0.002). The DFS was also reduced significantly in patients with Luminal B tumors than Luminal A tumors (log rank=7.09, p=0.007). The poor disease outcome in those patients may due to have increased plasma IGF-I, activated tissue pAkt and loss of functional FOXO1 A. Conclusions: Our study suggests a highest prevalence of basal-like tumors (triple negative) in premenopausal African American women, followed by premenopausal Latina women. Premenopausal Latina women also had a higher prevalence of HER2+/ER-tumors. DFS was poor in both ethnic groups with either basal like tumors or those with HER2+/ER-tumors. Activation of pAkt in the tumor tissue was a significant contributor to the poor disease outcome. Citation Information: Cancer Epidemiol Biomarkers Prev 2010;19(10 Suppl):A96.