Researchers in the Mayo Clinic Center for Individualized Medicine have been studying the community of bacteria, known as the microbiome, that live in many areas of our body for clues about how these bacteria help us stay healthy or cause disease.

In fact, investigators have already discovered that when the microbiome is in balance, these bacteria help us digest our food, boost our immune system and improve our brain function.

At the same time, researchers know that imbalances in the microbiome may be connected to the development of diseases in the stomach, liver, colon, lungs and skin.

Now a Mayo Clinic study shows that changes in the microbiome may also provide clues about the development of breast cancer.

Breast cancer is still difficult to predict and is the second most common cancer diagnosed in women. This new study highlights how studying changes in the microbiome may lead to the development of better diagnostic tests and treatments for breast cancer.

Dr. Nicholas Chia

"We have known for a long time that environmental factors play an important role in cancer. The microbiome provides both an indicator and an influence of the microenvironment within which cancer arises, making it a powerful avenue to go beyond host genetics," says Nicholas Chia, Ph.D., assistant professor of Biophysics and Surgery in the Center for Individualized Medicine Microbiome Program.

Read the full release about the study below.

A team of Mayo Clinic researchers has identified evidence of bacteria in sterilely-obtained breast tissue and found differences between women with and without breast cancer. The findings are published in the Aug. 3 issue of Scientific Reports.

Dr. Tina Hieken

“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. Furthermore, we identified significant differences in the breast tissue microbiome of women with cancer versus women without cancer,” says
Tina Hieken, M.D., a breast surgical oncologist at Mayo Clinic.

“Our work confirmed the presence of a distinct breast tissue microbiome and that it is different than the microbiome of the overlying breast skin.”

According to the National Cancer Institute, a microbiome is a collection of microorganisms and viruses that live in a specific environment in the human body.

Dr. Hieken says, globally, breast cancer accounts for nearly one quarter of all cancers and is the leading cause of cancer death among women. She says that 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 for individual women.

Dr. Amy Degnim

“Differences in the microbiome have been implicated in cancer development at a variety of body sites including stomach, colon, liver, lung and skin,” says co-investigators Amy Degnim, M.D., a breast surgical oncologist at Mayo Clinic.

“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 microorganisms or restoring normal microbiota may reverse this process,” adds Dr. Chia.

Dr. Hieken says 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. However, she says the findings of this study will spur further research to identify potential causes of breast cancer development and new microbial-based prevention therapies.

Co-authors are:

Tina Hieken, M.D.
Jun Chen, Ph.D.
Tanya Hoskin, M.S.
Marina Walther-Antonio, Ph.D.
Stephen Johnson
Sheri Ramaker
Jian Xiao, Ph.D.
Derek Radisky, Ph.D.
Keith Knutson, Ph.D.
Krishna Kalari, Ph.D.
Janet Yao
Larry Baddour, M.D.
Nicholas Chia, Ph.D.
Amy Degnim, M.D.

All co-authors are from Mayo Clinic.

The authors wish to thank the women who participated in this study and Michelle Neseth for her administrative support.

The study was supported by grants from the American Society of Breast Surgeons Foundation, The Fraternal Order of Eagles Cancer Research Fund, the Mayo Clinic Department of Surgery Research Unit and Mayo Center for Individualized Medicine.

Join us to learn more about the microbiome and other aspects of precision medicine

Learn more about ongoing research efforts in the Center for Individualized Medicine’s Microbiome Program, including a list of current research projects and stories about how this research has helped patients.

Hear experts discuss the latest research in precision medicine, including exploration of the microbiome, and how it can be applied to improve treatments for many conditions, such as heart disease, cancer, rheumatoid arthritis, Alzheimer's disease and autism.

Attend Individualizing Medicine 2016: Advancing Care Through Genomics. The Mayo Clinic Center for Individualized Medicine, is hosting the fifth annual genomics conference, October 5–6, in Rochester, Minn.

For a complete schedule and list of speakers, visit the conference website.  You may also learn more about the conference on the video blog series, “Story by Story.”   Follow the latest news related to the conference on the Center for Individualized Medicine blog, Facebook or Twitter at @MayoClinicCIM and use the hashtag #CIMCon16.

The Mayo Clinic Center for Individualized Medicine is hosting the conference with support from the Satter Foundation.

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