Results of a ground-breaking new study linking certain types of bacteria to breast cancer, carried out at the Canadian Centre for Human Microbiome and Probiotic Research in Ontario, have recently been published in the journal ‘Applied and Environmental Microbiology’.

Canadian research suggests that bacteria could have a role to play in breast cancer

The study looked at biopsy samples from 58 women that had undergone lumpectomies for either benign (13 women) or malignant (45 women) tumours and compared them with tissue samples from 23 healthy women that had had cosmetic breast reduction procedures.

Results showed that the women with breast cancer had higher levels of certain species of pathogenic bacteria, namely: Staphylococcus epidermidis and Escherichia coli than those women with healthy breasts. Conversely, the tissue samples taken from women with healthy breasts, had much higher levels of probiotic bacteria, such as Lactobacilli and Streptococcus species.

The different species of bacteria in the samples were determined by DNA sequencing, and then the organisms were cultured to ensure that they were still alive.

The research team

The research team was headed up by Dr Gregor Reid, who decided to look in to the potential role of bacteria in the development of breast cancer, in follow up to the finding that breast cancer often decreases with breast feeding.

It is known that breast milk contains probiotic species of bacteria, so Dr Reid wondered if it could be the bacteria in breast milk that was exerting a beneficial effect over the cancers of breast feeding mums.

In order to embark upon this research, Dr Reid had to first prove that bacteria are indeed present in breast tissue at all, a fact that he successfully proved in an earlier research project.

Whilst it is not fully understood how certain species of bacteria could cause breast tumour growth whilst other species appear to be protective, it is known that both Staphylococcus epidermidis and Escherichia coli both cause double-stranded breaks in DNA in laboratory cultured human cells.

Reid explains that ‘’double-strand breaks are the most detrimental type of DNA damage and are caused by genotoxins, reactive oxygen species and ionizing radiation.’’ He goes on to say that ‘’the repair mechanism for double-stranded breaks is highly error prone, and such errors can lead to cancer’s development.’’

The chemo-protective effects of the probiotic strains on the other hand, most likely comes from their ability to produce antioxidants that neutralize cell damaging reactive oxygen species.

Further research

It is important to mention that whilst this research is exciting, it was a very small study, and would need to be replicated in larger scale trials before any true conclusions could be made. I certainly wouldn’t want anybody reading this blog to think that taking probiotics could help with a cancer diagnosis. However, what is interesting to me is the fact that we now know that breast tissue even contains live bacteria, and that the implications of this new knowledge are being looked at by researchers around the world.

Once again I find myself amazed and fascinated at the far-reaching effects of our various microbial colonies. They impact our health on so many different levels, and we're still only breaking the tip of the iceberg with regards to research.

If you are interested in the subject of probiotics and cancer research you may also like to read:

'A new study suggests that certain probiotics could detect liver cancer'

'Vaginal bacteria strain shows anti-cancer properties.'


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