Breast Cancer and Its Relationship with the Microbiota

Abstract

The microorganisms that live symbiotically in human beings are increasingly recognized as important players in health and disease. The largest collection of these microorganisms is found in the gastrointestinal tract. Microbial composition reflects both genetic and lifestyle variables of the host. This microbiota is in a dynamic balance with the host, exerting local and distant effects. Microbial perturbation (dysbiosis) could contribute to the risk of developing health problems. Various bacterial genes capable of producing estrogen-metabolizing enzymes have been identified. Accordingly, gut microbiota is capable of modulating estrogen serum levels. Conversely, estrogen-like compounds may promote the proliferation of certain species of bacteria. Therefore, a crosstalk between microbiota and both endogenous hormones and estrogen-like compounds might synergize to provide protection from disease but also to increase the risk of developing hormone-related diseases. Recent research suggests that the microbiota of women with breast cancer differs from that of healthy women, indicating that certain bacteria may be associated with cancer development and with different responses to therapy. In this review, we discuss recent knowledge about the microbiome and breast cancer, identifying specific characteristics of the human microbiome that may serve to develop novel approaches for risk assessment, prevention and treatment for this disease.

Microbiome and Breast Cancer: New Role for an Ancient Population

“…The difference in breast tissue microbiome profile between healthy individuals and patients with BC was also confirmed in another study (20). This difference was also observed in patients with BC at various clinical stages (39). There was a clinical trial (MICROMA) (NCT03885648) that evaluated contribution of bacteria, archaea, viruses, and fungi in breast tissue, stool, and urine samples with their alteration by environmental contaminants to the risk of BC.…”

High-resolution QTL mapping with Diversity Outbred mice identifies genetic variants that impact gut microbiome composition

“…Using the total set of genes from within all 58 statistically significant and suggestive QTL regions for taxa within the family Ruminococcaceae, we identified multiple networks, each of 35 functionally interrelated genes, enriched in disease pathways for ovarian, breast, and colon cancer. Evidence of functional associations between ovarian cancer and Ruminococcaceae is lacking, but various studies have confirmed findings showing increased Ruminococcaceae abundance in breast cancer patients compared to normal healthy individuals [Fernández et al 2018, Zhu et al 2018. While these studies did not uncover a directionality to this association, the significant differences in microbiome composition could be used as independent biomarkers of breast cancer [Zhu et al 2018].…”

“…While these studies did not uncover a directionality to this association, the significant differences in microbiome composition could be used as independent biomarkers of breast cancer [Zhu et al 2018]. In addition to specific links between the family Ruminococcaceae and breast cancer, associations between the gut microbiome and breast cancer have been flagged [Fernández et al 2018]. This includes associations between perturbations in the gut microbiome and circulating estrogen levels and metabolites, produced by several bacteria including Ruminococcaceae and also known as the estrobolome, which can affect the risk for breast cancer [Plottel andBlaser 2011, Fuhrman et al 2014].…”

Microbiome, bile acids, and obesity: How microbially modified metabolites shape anti‐tumor immunity

“…[169][170][171] In the obese breast, most studies show an increase in the Firmicutes/Bacteroidetes ratio compared to lean breast tissue, a broad biomarker of dysbiosis. 167 Examination of the local microbiome in BC compared to normal tumor-adjacent or normal mammary gland has revealed interesting alterations. 11,14,168,[172][173][174][175][176] The Western diet is associated with obesity and poor tumor outcomes.…”