Breast Microbiome and Cancer

Scientists recently discovered that bacteria living in the breast microbiome may play a role in preventing or progressing breast cancer. The team found that healthy breast tissue bacterial colonies that are often thought to be beneficial to health, while breast cancer patients displayed increased levels of Bacillus, Enterobacteriaceae, and Staphylococcus, which are potentially pathogenic. The study  indicates that diverse set of bacterial species occur naturally within breast tissue, which was previously considered a sterile environment.

In addition, researchers found that certain bacteria linked to high levels of damage to DNA were detected more often among samples from breast cancer patients compared with samples from patients without cancer.

Moreover, researchers also observed decreased abundances of lactic acid bacteria in samples from women with breast cancer compared to samples from women without. Previous research has shown lactic acid bacteria (LAB), including Lactobacillus and Bifidobacteria displays anticarcinogenic activity.

This research and its results indicate that the breast microbiome may play a role in mitigating breast cancer risk.

Breast Microbiome and Cancer Research

Samples were taken from the breast microbiome and surrounding healthy tissue from 45 women with a history of surgery for breast cancer. Additional samples of breast tissue were taken from 13 women with benign tumors of the breast and 23 women with no history of cancer that previously underwent breast augmentation or reduction surgery. State-of-the-art DNA sequencing identified the range of bacterial species found in each tissue sample.

Researchers found increased levels of bacteria known to cause damage to DNA by double-stranded breaks in women with breast cancer. Bacteria often considered beneficial to human health— Streptococcus and Lactococccus —were found in increased levels in samples from women without cancer.

This work creates opportunities for future testing if probiotic use can alter the breast microbiome and future risk of cancer.


Urbaniak, C., Gloor, G.B., Brackstone, M. et al. The microbiota of breast tissue and its association with tissues. Applied and Environmental Microbiology. 2016. doi: 10.1128/AEM.01235-16

Leave a Reply