Microbial Dysbiosis Is Associated with Human Breast Cancer Original paper
Researched by:
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Karen Pendergrass
ID
Karen Pendergrass
Karen Pendergrass is a microbiome researcher specializing in microbiome-targeted interventions (MBTIs). She systematically analyzes scientific literature to identify microbial patterns, develop hypotheses, and validate interventions. As the founder of the Microbiome Signatures Database, she bridges microbiome research with clinical practice. In 2012, based on her own investigative research, she became the first documented case of FMT for Celiac Disease—four years before the first published case study.
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Women’s Health
Women’s Health
Women’s health, a vital aspect of medical science, encompasses various conditions unique to women’s physiological makeup. Historically, women were often excluded from clinical research, leading to a gap in understanding the intricacies of women’s health needs. However, recent advancements have highlighted the significant role that the microbiome plays in these conditions, offering new insights and potential therapies. MicrobiomeSignatures.com is at the forefront of exploring the microbiome signature of each of these conditions to unravel the etiology of these diseases and develop targeted microbiome therapies.
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Breast Cancer
Breast Cancer
Traditionally linked to genetic predispositions and environmental exposures, emerging evidence highlights the microbiome as a critical and underappreciated factor influencing breast cancer progression, immune response, and treatment outcomes.
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Karen Pendergrass
Researched by:
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Karen Pendergrass
ID
Karen Pendergrass
Microbiome Signatures identifies and validates condition-specific microbiome shifts and interventions to accelerate clinical translation. Our multidisciplinary team supports clinicians, researchers, and innovators in turning microbiome science into actionable medicine.
Karen Pendergrass
What Was Studied?
This study examined the microbiota present in breast tumor tissue compared to paired normal breast tissue from the same individuals, as well as healthy breast tissue from individuals without breast cancer. Using next-generation sequencing and quantitative PCR, the research aimed to identify differences in microbial composition, bacterial load, and their potential impact on the tumor microenvironment and breast cancer progression.
Who Was Studied?
The study included 20 breast cancer patients with estrogen receptor-positive (ER+) tumors, for whom paired tumor and normal adjacent tissue were analyzed. Additional bacterial load analysis included 23 healthy controls undergoing reduction mammoplasty. Gene expression profiling was conducted on tissue from six breast cancer patients and three healthy individuals.
Most Important Findings
The study revealed distinct microbial signatures associated with breast cancer. Methylobacterium radiotolerans was significantly enriched in tumor tissue, while Sphingomonas yanoikuyae was more abundant in paired normal tissue. A strong inverse correlation between the abundance of these two species was observed in normal tissue, but not in tumor tissue. Importantly, bacterial load in tumor tissue was markedly reduced compared to both paired normal and healthy breast tissue, with advanced-stage tumors exhibiting the lowest bacterial counts. This reduction in bacterial load correlated with decreased expression of antibacterial response genes, including Toll-like receptors (TLR2, TLR5, and TLR9) and antimicrobial effectors like IL-12A and BPI.
These findings suggest that microbial dysbiosis and a diminished antibacterial immune response in tumor tissue may contribute to breast cancer progression. Additionally, the results highlight the potential diagnostic value of bacterial load as a marker for breast cancer staging.
Greatest Implications
The association between microbial dysbiosis and breast cancer offers novel insights into the disease’s pathogenesis. The depletion of beneficial bacteria, such as Sphingomonas yanoikuyae, and a reduced immune response may create a permissive environment for tumorigenesis. This study supports the exploration of microbiota as a diagnostic tool and potentially as a therapeutic target to restore a healthy microbial balance and enhance immune surveillance. The inverse correlation between bacterial load and tumor stage underscores its potential utility in disease staging and progression monitoring.
Breast Cancer
Traditionally linked to genetic predispositions and environmental exposures, emerging evidence highlights the microbiome as a critical and underappreciated factor influencing breast cancer progression, immune response, and treatment outcomes.