Microbiota of breast tissue and its potential association with regional recurrence of breast cancer in Korean women

Recent studies reported the dysbiosis of microbiome in breast tissue from patients with breast cancer and the association of microbiota with the progress of breast cancer. However, the etiology of breast cancer is still unclear and the role of microbiota in breast tissue is not clear. This is due to the complexity of breast cancer and the various influencing factors including racial and geographical difference on microbiota in breast tissue. In this study, we analyzed and compared 141 tissue microbiota in three different tissue types (tumor, adjacent normal and lymph node) from the same patients (n=47) with breast cancer in Korea. Proteobacteria and Firmicutes were predominant phyla in all tissue, and the microbiota did not different by tissue type. However, the microbiota was significantly separated into two cluster types even in the same tissue type, and the clinicopatholgical factors were differently correlated according to microbiota cluster types. The risk of regional recurrence was significantly different by microbiota cluster type. In predicted function analysis, the pentose and glucuronate interconversions were significantly different by microbiota types and Enterococcus was the main contributing genus in these differences. These results showed that the microbiota in breast tissue could interact with host and influence on the risk of regional recurrence. Although further studies are necessary to validate our results, this study extended the information of breast tissue microbiota from Korean women and results will be applied to develop novel prediction method and treatment of patient with breast cancer.