Like gut, breasts may have unique bacterial microbiome that prevents or promotes cancer


It is a well-known fact that each one of us has a unique bacterial colony residing in our gut that determines our susceptibility to stroke and chronic fatigue, as well as our propensity to gain or lose weight. According to a new research, a similar bacterial population exists in breast tissue, which in turn influences women’s cancer risk.

At present, scientists believe that only around 5 to 10-percent of all breast cancer cases stem from hereditary causes. This opens up a host of other factors that either prevent or promote malignancy, such as weight, age, race and so on. Several research dating back to the 1960s have linked pregnancy and breastfeeding with significantly lower breast cancer susceptibility.

Consequently, the risk of breast cancer has been found to be higher in women who haven’t experienced full-term pregnancy  beyond the age of 30. While the exact reason behind this isn’t fully known, researchers believe that the bacteria present in breast milk likely protects the mothers from breast cancer. As part of a 2014 study, a team of scientists from Canada-based Western University showed evidence that women’s breasts are actually home to a colony of bacteria.

These bacterial communities help maintain the health of breast tissue by prompting immune cells into action. For the current research, the scientists went about the task of identifying the types of bacteria living in the breast tissue, and then figuring out if the microbial colonies in breast cancer patients differ from those in healthy women. To that end, the team retrieved bacterial DNA samples from a group of 58 women who had undergone lumpectomies or mastectomies as treatment for benign (13 of them) as well as malignant tumors (remaining 45).

The specimens were then analyzed against similar samples taken from 23 completely healthy women. As  pointed out by the scientists, women who were previously diagnosed with breast cancer exhibited substantially higher levels of Enterobacteriaceae, Staphylococcus  and Bacillus in their breast tissue. These bacterial varieties are known to be responsible for creating double-stranded breaks in the human HeLa cells’ DNA. The researchers added:

Double-strand breaks are the most detrimental type of DNA damage.

Those among the healthy group, on the other hand, showed higher levels of Lactococcus and Streptococcus kinds, both of which boast powerful anti-carcinogenic properties. For instance, the bacterium Streptococcus thermophilus generates antibodies that work against a special class of molecules known as reactive oxygen species that afflicts DNA damage associated with cancer.

The double-stranded breaks in DNA, scientists believe, are actually the work of reactive oxygen species, meaning that certain women have bacteria in their breast tissue that promote the development of cancer. Speaking about the research, which was recently published in the Applied and Environmental Microbiology journal, Gregor Reid, a member of the team, said:

[The results] suggest that microbes in the breast, even in low amounts, may be playing a role in breast cancer – increasing the risk in some cases and decreasing the risk in other cases.

Despite the small sample size, the research and its findings could reduce women’s risk of breast cancer, which is currently the most common form of cancer in the female population across the world. If it is indeed true that certain bacteria help prevent breast cancer, administering them as probiotics could ensure a healthy breast microbiome. Reid went on to say:

 Colleagues in Spain have shown that probiotic lactobacilli ingested by women can reach the mammary gland. Combined with our work, this raises the question, should women – especially those at risk for breast cancer – take probiotic lactobacilli to increase the proportion of beneficial bacteria in the breast? To date, researchers have not even considered such questions, and indeed some have balked at there being any link between bacteria and breast cancer or health.

Source: EurekAlert!

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