Association between Gut Microbiota and Breast Cancer: Diet as a Potential Modulating Factor

Abstract

Breast cancer (BCa) has many well-known risk factors, including age, genetics, lifestyle, and diet; however, the influence of the gut microbiome on BCa remains an emerging area of investigation. This study explores the connection between the gut microbiome, dietary habits, and BCa risk. We enrolled newly diagnosed BCa patients and age-matched cancer-free controls in a case-control study. Comprehensive patient data was collected, including dietary habits assessed through the National Cancer Institute Diet History Questionnaire (DHQ). 16S rRNA amplicon sequencing was used to analyze gut microbiome composition and assess alpha and beta diversity. Microbiome analysis revealed differences in the gut microbiome composition between cases and controls, with reduced microbial diversity in BCa patients. The abundance of three specific microbial genera-Acidaminococus, Tyzzerella, and Hungatella-was enriched in the fecal samples taken from BCa patients. These genera were associated with distinct dietary patterns, revealing significant associations between the presence of these genera in the microbiome and specific HEI2015 components, such as vegetables and dairy for Hungatella, and whole fruits for Acidaminococus. Demographic characteristics were well-balanced between groups, with a significantly higher body mass index and lower physical activity observed in cases, underscoring the role of weight management in BCa risk. Associations between significant microbial genera identified from BCa cases and dietary intakes were identified, which highlights the potential of the gut microbiome as a source of biomarkers for BCa risk assessment. This study calls attention to the complex interplay between the gut microbiome, lifestyle factors including diet, and BCa risk.

Keywords: Acidaminococus; Hungatella; Tyzzerella; breast cancer; gut microbiome.

Figure 1

(a): Bar plots of the gut microbiota taxonomic profiles at the phylum level. (b): Top ten genus-level abundance stratified by case/control status. Relative abundance of taxonomic profile of BC and HC groups at phylum and genus levels.

Figure 2

Linear discriminant analysis effect size (LEfSe) analysis of fecal microbiome at genus level of the participants in the control and BCa group samples. An LDA (score > 2) effect size-based bar graph showed bacterial genus enriched in feces from cancer-free controls and BCa groups.

Figure 3

Relative abundances (%) of identified biomarker candidates’ taxonomic abundances by case-control status. Twenty-four percent of the cases (10/42) and 9% of the controls (4/44) have Acidaminococus in their microbiome. The relative abundances (%) of the participants who have Acidaminococus species in their gut microbiome ranges between 1.850% and 0.010%. Thirty-eight percent of the cases (16/42) and 9% of the controls (4/44) have Hungatella in their microbiome. Relative abundances (%) of the participants who have Hungatella species in their gut microbiome ranges between 0.980% and 0.010%. Thirty-eight percent of the cases (16/42) and 20% of the controls (9/44) have Tyzzerella. Relative abundances (%) of the participants who have Tyzzerella species in their gut microbiome ranges between 2.450% and 0.017%.