Healthy, cancerous breast tissue have different microbiomes, researchers say

Further research is needed to understand whether the difference between women with and without cancer is significant to the disease.

By Stephen Feller

ROCHESTER, Minn., Aug. 3 (UPI) -- Bacteria in the body are increasingly being implicated in the occurrence and severity of cancer. Researchers at Mayo Clinic now say differences in the microbiota of women with and without breast cancer suggest bacteria may play a role in the disease.

Researchers involved with the new study say a better understanding of bacteria in different parts of the body, and the differences between patients with and without cancer, could help better identify risk for breast cancer.


A microbiome is the collection of microorganisms that live in the body, each of which plays a role in the function of organs and bodily systems. Changes in microbiomes have been linked to stomach, colon, liver, lung and skin cancers, among others, say researchers.

"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," Dr. Nick Chia, a microbiome researcher at Mayo Clinic, said in a press release.

For the study, published in the journal Nature Reports, researchers obtained breast tissue samples from 33 patients, finding each had a microbiome similar to that of the patient's breast skin tissue, but distinctly different.


In addition to differences between skin and tissue samples, the researchers found the microbiota of normal breast tissue adjacent to invasive cancer was significantly different from that of normal breast tissue adjacent to benign tumors.

While the researchers say it is unclear whether small shifts in the microbial communities of tissue could cause cancer or make it worse, differences in between the microbiota of women with and without cancer require further study.

"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," said Dr. Tina Hieken, 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."

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