http://www.digitaljournal.com/science/beneficial-bacteria-protect-against-breast-cancer/article/468872

Beneficial bacteria protect against breast cancer

Posted Jun 29, 2016 by Tim Sandle
New research suggests that women who avoid breast cancer have a different microbial profile (microbiome) to those who are at a greater risk of contracting the disease.
To reach the conclusion (and one that's trending high on Twitter) that the microbiomes of some women differ to others, researchers genetically analysed DNA taken from breast tissue samples from various women. The women sampled, 58 in number, were undergoing mastectomies or lumpectomies. Of these, 13 women had benign tumors and 45 had cancerous tumors. To add to this number, samples were also taken from 23 women who had no tumors and had never had breast cancer. These women had, however, undergone either breast enhancements or reductions.
From the analysis of the samples, as reported by Pharmaceutical Microbiology, it was found that women with breast cancer had higher levels of two bacteria: Escherichia coli and Staphylococcus epidermidis. Previous studies had shown these organisms can cause double-stranded breaks in DNA human cells, and this form of DNA damage can trigger cancer.
Here lead researcher Professor Gregor Reid stated: “Double-strand breaks are the most detrimental type of DNA damage and are caused by genotoxins, reactive oxygen species, and ionizing radiation.”
In contrast to these potentially dangerous organisms, samples from women who had either benign tumors or no tumors at all had higher levels of different bacteria. Here so-called ‘beneficial bacteria’ were species of Lactobacillus and Streptococcus. These bacteria do not cause DNA damage. There is also a possibility that they can exert an anti-carcinogenic effect, at least according to the study authors.
These beneficial bacteria are associated with milk and the finding possibly tallies with other research which suggests that women who breast feed have lower rates of breast cancer compared with women who have never lactated.
Here Professor Reid adds: “Since human milk contains beneficial bacteria, we wondered if they might be playing a role in lowering the risk of cancer. Or, could other bacterial types influence cancer formation in the mammary gland in women who had never lactated? To even explore the question, we needed first to show that bacteria are indeed present in breast tissue?”
The findings may indicate, Bioscience Technology speculates, that probiotics could assist in resisting the disease. It should be noted, however, that probiotics remain a controversial subject and the evidence in support of ingesting specific live bacteria is variable.
The research is published in the journal Applied and Environmental Microbiology. The research is titled “The microbiota of breast tissue and its association with tumors.”