Crucial Link Between Bacteria and Breast Cancer Identified


A recent Canadian Study suggests that bacteria present in cancer patient’s breast have the potential to assist and modulate breast cancer development.

On the contrary, beneficial bacteria are present in healthy breasts which protect women from breast cancer. The study also claims that the daily intake of probiotics significantly reduces the risk of breast cancer.

western university

The research was conducted by Gregor Reid and his collaborators from Western University and Lawson Health Research Institute. Camilla Urbanik (Gregor Reid’s PhD student) collected 58 breast tissue samples of women undergoing lumpectomies or mastectomies for benign (13 women) and cancerous (45 women). 23 healthy samples were obtained from healthy women who had undergone breast reduction or enhancements surgeries. The bacteria present in the samples were identified and matched by DNA sequencing (16S rRNA amplicon sequencing) and cultured to confirm the status of bacteria.

microbiota in breast tissue

Figure 1. Breast tissue microbiota in 43 Canadian women identified by 16S rRNA amplicon sequencing (photo credit: Urbaniak et al.,  doi: 10.1128/AEM.01235-16, AEM.01235-16).

According to Reid, target specific antibiotic treatment is the other answer for breast cancer treatment and management.

The results revealed the difference in the microbiota present in the cancerous and healthy tissues. Though both the group showed anti-carcinogenic properties but the presence of health-promoting bacteria (Lactobacillus and Streptococcus) were prevalent in healthy tissues. Increased level of Escherichia coli and Staphylococcus epidermidis was found in the cancerous tissues. Bacteria obtained from cancerous tissue in γH2AX assay induced DNA double stranded breaks in HeLa cells (cultured human cells).

The investigators explained “Double-strand breaks are the most detrimental type of DNA damage and are caused by genotoxins, reactive oxygen species, and ionizing radiation. The repair mechanism for double-stranded breaks is highly error prone, and such errors can lead to cancer’s development.


Reason of DNA Breakage in presence of Streptococcus thermophilus

The researchers explained that presence of low level of natural killer cells (also known as immune cells) protects and controls tumor growth and hence fight against cancer. These cells are significantly reduced when Streptococcus thermophilus increases in number. Streptococcus thermophilus produces antioxidants that neutralize the reactive oxygen species, which induces DNA breakage and finally cancer. This is where probiotics comes into play as intake of probiotic can replace harmful ones by beneficial bacteria reducing the risk of DNA breakage and overall decreasing the risk of cancer by their anti-carcinogenic properties.

breast cancer dna damage

Figure 2. DNA damage ability of E.coli isolated from breast cancer patients  (photo credit: Urbaniak et al.,  doi: 10.1128/AEM.01235-16, AEM.01235-16).

This study was started in 2014 where it was proved that the breast tissue is not sterile and in fact is the host for diverse population. The knowledge that breastfeeding reduces the risk of breast cancer along with the inquisitiveness to find, whether the beneficial bacteria present in human milk can reduce the risk of breast cancer motivated Gregor Reid to work on this topic.

Several universities and institutes are working together in this research. Researcher working in Spain concluded that probiotic lactobacilli ingested by women can reach the mammary gland and the growth of bacteria might be independent of lactation.

According to Reid, the established link between breast cancer and bacteria surge for many questions in the researcher community that still need to be answered like the significance of consumption of probiotic bacilli in women at high breast cancer risk or conditions which keep check on these bacteria and so on.

Since the research is still in budding stage question are many but answers are few and far. But George Reid and his team of collaborators is expecting that further research may result in the use of probiotics in future, as drug therapy treatments for cancer.

Featured image credit: Dividing breast cancer cell. © (Stock Photo ID: 93129908)

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