Researchers examined the bacterial makeup of breast tissue in women with breast cancer and found that it has insufficient levels of a certain bacterial genus called Methylobacterium.

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By analyzing breast tissue samples, researchers show that a bacterial imbalance is associated with breast cancer development.

The human microbiome, or the total number of bacteria living in the human body, is known to play a key role in the development of many diseases.

In particular, the bacteria living in our gut have been linked to numerous conditions, ranging from type 2 diabetes to Parkinson’s disease, and even multiple sclerosis.

Previous studies have also examined the link between gut microbiota and the development of breast cancer. These studies have suggested that the microbes in the gut may regulate estrogen levels, leading to estrogen-receptor positive breast cancer.

But less attention has been paid to the microbiome residing in the breast tissue of breast cancer patients. Now, researchers break new ground by uncovering the bacterial composition in the breast tissue of cancer patients.

Dr. Charis Eng, chair of the Cleveland Clinic’s Genomic Medicine Institute in Ohio, led the study with Dr. Stephen Grobmyer, director of Breast Services at the Cleveland Clinic.

Hannah Wang, a researcher at the Cleveland Clinic’s Lerner Research Institute of the Genomic Medicine Institute, is the first author of the new study, which was published in the journal Oncotarget.

Wang and colleagues examined the breast tissue of 78 women – 57 of whom had undergone a mastectomy because they had invasive breast cancer, and 21 of whom were healthy and had undergone cosmetic breast surgery.

In addition to the breast tissue microbiome, the scientists examined the urinary and oral bacteria of these women.

The study found that breast cancer patients had considerably lower levels of a bacterial genus called Methylobacterium.

Additionally, the results showed higher levels of so-called gram-positive bacteria in urine, including Staphylococcus, Corynebacterium, Propionibacteriaceae, and Actinomyces.

More research is needed, the authors note, to understand the role of these bacteria in breast cancer. The findings also need “a larger cohort of clinically matched patients” to be validated.

However, the research remains “one of the largest studies to examine the microbiome in human breast cancer patients,” write the authors.

To my knowledge, this is the first study to examine both breast tissue and distant sites of the body for bacterial differences in breast cancer […] Our hope is to find a biomarker that would help us diagnose breast cancer quickly and easily.”

Dr. Charis Eng

“In our wildest dreams,” says Dr. Eng, “we hope we can use microbiomics right before breast cancer forms and then prevent cancer with probiotics or antibiotics.”

“If we can target specific pro-cancer bacteria,” adds Dr. Grobmyer, “we may be able to make the environment less hospitable to cancer and enhance existing treatments.”

“Larger studies are needed,” he says, “but this work is a solid first step in better understanding the significant role of bacterial imbalances in breast cancer.”

Both co-senior authors are currently working with other researchers on using nanotechnology to target specific bacteria involved in breast cancer.

Future nanotechnology-based treatments could deliver antibiotics straight to the relevant bacteria.