Researchers identify unique breast microbiome

Volume 5, Issue 4, 2016


These findings may help identify potential causes of breast cancer and encourage new therapies.

Photograph of Tina J. Hieken, M.D.

Tina J. Hieken, M.D.

Photograph of Amy C. Degnim, M.D.

Amy C. Degnim, M.D.

A team of Mayo Clinic researchers has identified evidence of bacteria in breast tissue and found differences between women with and without breast cancer.

These research findings were published in the August 3, 2016, issue of Scientific Reports.

"Our research found that breast tissue samples obtained in the operating room under sterile conditions contain bacterial DNA, even when there is no sign of infection," said Tina J. Hieken, M.D., a breast surgical oncologist at Mayo Clinic in Rochester, Minnesota. "Furthermore, we identified significant differences in the breast tissue microbiome of women with cancer versus women without cancer and the presence of a distinct breast tissue microbiome, and that it is different than the microbiome of the overlying breast skin."

A microbiome is a collection of micro-organisms and viruses that live in a specific environment in the human body.

Breast cancer accounts for nearly one-quarter of all cancers globally and is the leading cause of cancer death among women. While there are established risk factors for breast cancer, at least 70 percent of breast cancer cases occur in women of average risk, and current prediction models are poor at identifying risk of cancer for individual women, Dr. Hieken said.

"Differences in the microbiome have been implicated in cancer development at a variety of body sites, including the stomach, colon, liver, lung and skin," said co-investigator Amy C. Degnim, M.D., a breast surgical oncologist at Mayo Clinic in Rochester.

"There is mounting evidence that changes in the breast microbiome may be implicated in cancer development and the aggressiveness of cancer, and that eliminating dangerous micro-organisms or restoring normal microbiota may reverse this process," said Nicholas Chia, Ph.D., a microbiome researcher at Mayo Clinic in Rochester.

It remains unclear whether small shifts in microbial communities, the presence of a virulent pathogenic strain or the absence of a beneficial one might be responsible for promoting the development of cancer in the breast microbiome, Dr. Hieken said. However, findings from this study will spur further research to identify potential causes of breast cancer development and new microbial-based prevention therapies.