Distinct microbial communities that differ by race, stage, or breast-tumor subtype in breast tissues of non-Hispanic Black and non-Hispanic White women

Alana Smith,Gregory Vidal,Elizabeth Tolley,Athena Starlard-Davenport,Joseph F Pierre,Liza Makowski,Beverly Lyn-Cook,Lu Lu

doi:10.1038/s41598-019-48348-1

Abstract

Growing evidence highlights an association between an imbalance in the composition and abundance of bacteria in the breast tissue (referred as microbial dysbiosis) and breast cancer in women. However, studies on the breast tissue microbiome have not been conducted in non-Hispanic Black (NHB) women. We investigated normal and breast cancer tissue microbiota from NHB and non-Hispanic White (NHW) women to identify distinct microbial signatures by race, stage, or tumor subtype. Using 16S rRNA gene sequencing, we observed that phylum Proteobacteria was most abundant in normal (n = 8), normal adjacent to tumor (normal pairs, n = 11), and breast tumors from NHB and NHW women (n = 64), with fewer Firmicutes, Bacteroidetes, and Actinobacteria. Breast tissues from NHB women had a higher abundance of genus Ralstonia compared to NHW tumors, which could explain a portion of the breast cancer racial disparities. Analysis of tumor subtype revealed enrichment of family Streptococcaceae in TNBC. A higher abundance of genus Bosea (phylum Proteobacteria) increased with stage. This is the first study to identify racial differences in the breast tissue microbiota between NHB and NHW women. Further studies on the breast cancer microbiome are necessary to help us understand risk, underlying mechanisms, and identify potential microbial targets.

Highlights

Breast cancer is the most common cancer in women worldwide[1]
non-Hispanic Black (NHB) women are more likely to be diagnosed with an aggressive form of breast cancer, known as triple negative breast cancer (TNBC) that does not respond to hormonal breast cancer therapies[4,5]
The cause for the racial disparities in breast cancer risk and outcomes observed between NHB and non-Hispanic White (NHW) women is unclear; mounting evidence suggests that an imbalance in the collective genome of microorganisms, referred to as microbial dysbiosis, may be associated with the development of human diseases including cancer[6,7,8]

Summary

Introduction

In the United States, more than 200,000 new breast cancer cases will be diagnosed this year alone[2] Of these women, non-Hispanic black (NHB) women are more likely to die from breast cancer compared to other racial/ethnic groups[3]. Breast tissues have been observed to have their own unique microbiome that is distinct between pathologically defined normal, benign, and malignant breast tissues[6,9,10,11]. These studies did not include NHB women in their analysis. An altered microbiome and should be measured in all breast cancer studies to better understand how microbial dysbiosis influences breast cancer development and outcomes in ethnically diverse populations and if biomarkers can be identified to stratify risk or response to treatment

Methods

Results

Conclusion