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

What was studied?

This study investigated the association between the gut microbiome, dietary intake, and breast cancer using a case-control design. The focus keyphrase association between gut microbiota and breast cancer appears throughout the study, which examined whether specific gut microbial signatures and diet-related patterns distinguish newly diagnosed breast cancer patients from cancer-free controls. Using 16S rRNA sequencing, researchers profiled microbial diversity and taxonomic composition, then integrated these findings with detailed dietary assessments derived from the NCI Diet History Questionnaire. The study further evaluated whether dietary components from the Healthy Eating Index–2015 correlated with breast cancer–associated microbial genera. By combining microbiome profiling with lifestyle and dietary data, the investigation aimed to clarify how microbial ecology and diet might contribute to breast cancer risk or serve as early biomarkers.

Who was studied?

Participants were 42 newly diagnosed, treatment-naïve breast cancer patients and 44 age-matched cancer-free controls recruited at Oregon Health & Science University. All were women aged 20–89 years, English-speaking, and able to provide informed consent. Controls were required to have recent, non-suspicious mammograms, and both groups completed extensive demographic, lifestyle, and dietary questionnaires. Fecal samples were collected for microbiome sequencing. The two cohorts were demographically comparable, though breast cancer cases had significantly higher BMI and lower physical activity. Emotional stress levels were also higher among cases. This well-defined cohort allowed examination of microbial differences with minimized demographic confounding.

Most important findings

Breast cancer patients showed significantly reduced gut microbial alpha diversity across Shannon, Observed, Inverse Simpson, and Pielou indices, indicating dysbiosis. Beta-diversity differed by Jaccard distance, suggesting compositional variation driven partly by the presence/absence of taxa. LEfSe analysis identified three genera enriched in breast cancer: Acidaminococcus, Hungatella, and Tyzzerella. Ten genera were enriched in controls, including Christensenellaceae, Dialister, Romboutsia, and others. Figures on pages 8–9 visually depict these shifts, with a higher relative abundance of the three breast-cancer-associated genera among cases. Diet–microbiome associations revealed that Acidaminococcus presence correlated with lower whole-fruit intake, Hungatella with lower dairy intake and higher total vegetable intake, and Tyzzerella showed no dietary association. These links suggest diet-shaped microbial niches may influence or reflect breast cancer–related microbial patterns.

Key implications

Findings underscore the potential for gut microbial signatures—particularly Acidaminococcus, Hungatella, and Tyzzerella—to serve as biomarkers for breast cancer risk or early detection. Reduced microbial diversity reinforces the concept of breast-cancer-associated dysbiosis, aligning with prior research on inflammation, estrogen metabolism, and microbial metabolites. Dietary components influencing these taxa highlight modifiable nutritional pathways that may alter microbial risk profiles. Although causal relationships cannot be established from this design, the work supports future research integrating fecal metabolomics, dietary interventions, and mechanistic studies to clarify how microbial activity contributes to breast cancer pathogenesis. Ultimately, the study frames the gut microbiome as a clinically relevant factor in breast cancer prevention and risk assessment.

Citation

Altinok Dindar D, Chun B, Palma A, et al. Association between gut microbiota and breast cancer: Diet as a potential modulating factor.Nutrients. 2023;15(4628). doi:10.3390/nu15214628