Breast Cancer and the Human Oral Microbiome
Creators: name: University Of California Office Of The President
Publisher: name: University of California Office of the President
publisherIdentifier: https://ror.org/00dmfq477
publisherIdentifierScheme: ROR
Year: 2024

description: Non-technical overview of the research topic and relevance to breast cancer:
 
 
 
 The human body contains ten times more bacterial cells than human cells. We now know that there is an interplay between these bacteria that we carry and our bodies, in both health and when there is disease present. These bacteria largely enter the body through the mouth and the mouth contains a diverse array of microbial species. In the context of periodontal (gum) disease, these microbes cause inflammation in the mouth. Interestingly, there are reported associations between periodontal disease and a variety of other disorders, including breast cancer. The rationale behind this association is that inflammation is a major factor in both periodontal disease and cancer. Recent studies have examined the oral microbiome (the collection of all the different microbes present in the mouth) of healthy individuals, but how this relates to health and disease remains largely unexplored. Understanding how oral microbial diversity relates to breast cancer will open up new opportunities for the development of novel markers for early detection (or markers of susceptibility) as well as new strategies for prevention. For example, perhaps altering the oral microbiome through better oral hygiene or through the use of probiotics (health promoting microbes “friendly” bacteria often found in yogurt and kefir, for example) would shift a person from having a “cancer microbial profile” to a “healthy microbial profile”, thereby reducing a person’s risk of developing breast cancer.
 
 
 
 
 
 
 
 The question(s) or central hypotheses of the research: 
 
 
 
 We hypothesize that there is a link between breast cancer and the oral microbiome. We propose to explore this link by describing and comparing the oral microbes present in the saliva of women with early stage invasive breast cancer, women with DCIS, and healthy women. Although the microbiome contains bacteria, fungi, and viruses, for the purpose of this project we are limiting our study to just the bacterial component of the microbiome. Since oral bacteria associated with some diseases have been found at sites distant from the mouth (examples include atherosclerotic plaques and colorectal cancer tissue), we will also determine whether there are differences in the microbial diversity found within breast cancer tissue compared to healthy breast tissue. 
 
 
 
 
 
 
 
 The general methodology:
 
 
 
 Women with early stage invasive breast cancer, women with DCIS, and healthy women will rinse their mouths with a mouthwash solution in order for us to collect the bacteria present. Breast tissue samples will be obtained from breast cancer patients undergoing standard of care surgical resection of their tumors, and from healthy women undergoing reduction mammoplasty (breast reduction). Since many of the bacteria that make up the human microbiome have not been successfully cultured, we will use a genomics approach to determine the microbial diversity in these samples. DNA will be isolated from these specimens and a portion of a bacterial gene (the 16S rRNA gene) will be amplified using the polymerase chain reaction (PCR) and sequenced using high throughput Next Generation sequencing. The 16S rRNA gene is considered the gold standard for studies of microbial communities and for assigning taxonomic names to bacteria. In a small pilot study using this technique, we identified over 300 different bacteria species in oral rinse samples. 
 
 
 
 
 
 
 
 Innovative elements of the project: 
 
 
 
 This proposed project is innovative from a few perspectives: Study concept: we are investigating a novel research question –Is there a link between the oral microbiome and breast cancer? Recent studies have examined microbial diversity in the oral cavity in healthy individuals, but to date there are no studies on how this relates to breast cancer. Nor are there studies examining the microbial diversity associated with healthy or malignant breast tissue. Research method or technology: the recent advent of large-scale parallel sequencing methodologies now makes it possible to address questions relating to microbial diversity, be it in the oral cavity, skin, gut, tumor tissues, etc., and its relationship to various diseases. Clinical interventions: we are using a novel approach to develop potential biomarkers for early detection. Namely, we hope to identify patterns of microbial diversity that distinguish breast cancer patients from healthy people. That could then be developed into an early screening test.