I OFTEN HEAR THAT WE ALL HAVE A GUT MICROBIOME, a bacterial environment lining our intestines. The microbiome plays a role in everything from mental health to fitness to weight control. Did you know your breast has a microbiome, which may influence breast cancer risk?
Breast cancer specialists believe only five to 10 percent of the disease is hereditary.
Other contributing factors include age, female sex, weight, alcohol consumption, smoking, number of menstrual cycles, race, and previous cancer treatments.
Could the breast microbiome influence cancer risk?
Why I Write Today
Breast cancer is common, directly affecting 13 percent of American women in their lifetime.
This percentage means there is a one in eight chance she will develop breast cancer. There is a seven-in-eight chance she will never have the disease.
In recent years, incidence rates have increased by 0.5 percent per year. But there is some good news: Breast cancer death rates have been dropping steadily since 1989, for an overall decline of 43 percent through 2020.
The decrease in death rates is likely due to earlier detection (through screening and awareness) and better treatments. Still, the decline has slowed slightly in recent years.
So many of my patients immediately ask, “Why did I get breast cancer?” I saw six patients with the disease this week, and all but one wondered about the causes of their cancer.
While we know many breast cancer risk factors, we cannot confidently say why any individual gets cancer.
A new research pathway offers another possible explanation for why breast cancer occurs.
Microbiome
The microbiome is a complex and intricate ecosystem of microorganisms that inhabit the human body and play a crucial role in our overall health and well-being.
This fascinating and relatively recent area of scientific exploration has revealed that our bodies are not just comprised of human cells but are also teeming with trillions of microorganisms, including bacteria, viruses, fungi, and other microbes.
I love this microbiome description:
“Picture a bustling city on a weekday morning, the sidewalks flooded with people rushing to get to work or to appointments. Now imagine this at a microscopic level and you have an idea of what the microbiome looks like inside our bodies, consisting of trillions of microorganisms (also called microbiota or microbes) of thousands of different species.”
Microbiome Implications
These microscopic inhabitants collectively form the microbiome, a dynamic and interconnected community that resides in various parts of our bodies, with the gut being one of the most extensively studied microbiome habitats.
The microbiome is like a bustling metropolis within our bodies, where microbial citizens engage in many activities, including digesting food, supporting the immune system, producing essential vitamins, and influencing our mood and behavior.
The composition of an individual’s microbiome can be highly unique and influenced by various factors such as genetics, diet, environment, and lifestyle.
The Microbiome and Breast Cancer
Over the last several years, we have discovered that each of us has a unique microbial environment in our intestines. This microbiome is important for health.
Scientists have recently shown that microbes also exist in female breast tissue; the microbiome plays a role in a woman’s breast cancer risk.
I was surprised to learn that until just two years ago, scientists had believed breast tissue was sterile — meaning it contains no bacteria or other microbes.
A 2014 paper turned that view upside down:
Western University (Canada) scientists revealed that breasts contain a diverse community of bacteria, which could contribute to the maintenance of healthy breast tissue by stimulating nearby immune cells.
What are the implications of the finding that the breast has a microbiome?
Breast Microbiome and Cancer Risk
The Canadian research team conducted a new study to determine the bacteria types in breast tissue.
Furthermore, they wanted to see if bacterial populations differ in individuals with and without breast cancer.
First, the researchers analyzed bacterial DNA from breast tissue samples from 58 women having surgery for benign (13 subjects) or cancerous tumors (45 subjects).
The team then compared the samples to 23 healthy women with no breast cancer diagnosis.
Breast Microbiome and Cancer Study Results
The research findings are intriguing and hypothesis-generating:
Women with breast cancer had higher levels of Enterobacteriaceae, Staphylococcus, and Bacillus bacteria. Prior studies show these species can induce double-stranded breaks in DNA in human HeLa cells — DNA damage linked to cancer development.
On the other hand, those without breast cancer had higher incidences of Lactococcus and Streptococcus bacteria. These strains may have powerful anti-cancer properties.
Breast Microbiome Study Implications
I find the researcher’s observations fascinating.
According to the team, Streptococcus thermophilus produces antioxidants that can neutralize a class of molecules called reactive oxygen species. Reactive oxygen species can cause DNA damage linked to cancer.
Remember the double-strand breaks that I mentioned above, the ones that are linked to cancer development? Women may have breast bacteria that encourage breast cancer development; others may help prevent it.
My Thoughts
The study is quite small and does not capture the diversity of women worldwide.
Still, if additional research confirms the hypothesis that bacterial populations increase (or decrease) breast cancer risk, we may be able to lower the risk by manipulating the breast microbiome.
I wonder if bacteria in breast milk may help protect the mother from breast cancer. We know that breastfeeding lowers cancer risk.
Reducing Breast Cancer Risk
While I do not have specific advice about how to improve your breast microbiome, there are some steps you can take to drop your breast cancer risk. The U.S. Centers for Disease Control (CDC) recommends the following:
- Keep a healthy weight.
- Be physically active.
- Choose not to drink alcohol or drink alcohol in moderation.
- If you are taking or are considering oral contraceptives (birth control pills) or hormone replacement therapy, ask your healthcare provider about the risks and determine if it is right for you.
- Breastfeed your children if you are able.
- If you have a family history of breast cancer or inherited changes in BRCA1 and BRCA2 [or other] genes, please talk to your healthcare provider about other ways to reduce your cancer risk.
Staying healthy throughout your life can reduce your odds of getting cancer and improve your chances of surviving if it occurs.
Thank you for reading “Breast Microbiome and Cancer Risk.”
