Abstract B26: Comparative analysis of breast tumor microbiome in Black non-Hispanic (BNH) and White non-Hispanic (WNH) women

Abstract

African American women are approximately twice as likely to be diagnosed with highly aggressive estrogen receptor-negative (ER-) and TNBC subtypes of breast cancer than Caucasian women. Among biologic factors, microbiota has been implicated in the etiology of several kinds of cancer including breast cancer. Few recent studies have shown that the breast niche-specific microbiota may have a major influence on breast tumorigenesis as shown by a decreased abundance of bacterial species with known immunomodulatory and probiotic effect in paired tumor tissue as compared to normal tissue derived from healthy patients, including different microbiota profiles in different subtypes of breast cancer. To understand whether the breast tissue harbors microbiota profiles that are uniquely race-specific we have analyzed tumor and matched normal and tumor tissue using 16S rRNA targeted sequencing strategy. Two distinct breast tumor types derived from women were included in this study: triple-negative breast cancer (TNBC) and triple-positive breast cancer (TPBC) derived from BNH and WNH women. The data were analyzed for microbiota composition, abundance, and diversity parameters, alpha diversity and beta diversity. The preliminary microbiome analysis revealed specific differences in abundance both at the phylum and genus levels between WNH and BNH women breast tissues; the alpha diversity matric, Shannon index measuring both richness and evenness of microbiota diversity showed differences in microbial diversity between normal breast tumor tissue and the matched normal adjacent to tumor tissue. The microbiota richness was relatively lower in BNH TNBC tumor tissue as compared to its matched normal adjacent to tumor zone as defined by pathologic analysis. In contrast, the microbiota richness was higher in WNH TNBC tumor tissue as compared to its matched normal breast tissue. The multivariate analysis of beta diversity revealed a distinct clustering in BNH and WNH TNBC microbiota between both tumors as compared to normal tissue and BNH as compared to WNH racial groups. Research reported in this publication was supported by the National Institute on Minority Health and Health Disparities of the National Institutes of Health under Award Numbers S21MD012472 and U54MD006882. Note: This abstract was not presented at the conference. Citation Format: Srikantha Thyagarajan, Yan Zhang, Santosh Thapa, Michael S. Allen, Nicole Phillips, Jamboor K. Vishwanatha. Comparative analysis of breast tumor microbiome in Black non-Hispanic (BNH) and White non-Hispanic (WNH) women [abstract]. In: Proceedings of the AACR Special Conference on the Microbiome, Viruses, and Cancer; 2020 Feb 21-24; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2020;80(8 Suppl):Abstract nr B26.