Abstract Background While lifestyle factors are known to be associated with breast cancer development, the potential role of the gut microbiome, which is influenced by lifestyle, as a risk factor is not well understood. We conducted a comparative analysis of the intestinal microbiota between healthy individuals and breast cancer patients to investigate the potential impact of gut microbiome composition on breast cancer development. This study aimed to explore the role of intestinal microbial communities in breast cancer pathogenesis. Methods We conducted a comparative analysis of fecal 16S rRNA amplicon sequencing data from 100 individuals in the general population and 79 breast cancer patients. We investigated the differences between the two groups in terms of relative abundance, absolute quantity, diversity, and functionality of the gut microbiota. Results Breast cancer groups showed higher levels of Firmicutes and lower levels of Bacteroidota at the phylum level, and an increase in Fusobacteriota was found in the human epidermal growth factor receptor 2 (HER2)-negative breast cancer group. Additionally, certain genera were more or less common in breast cancer groups at the genus level. The study also indicated lower gut microbiota diversity and loss of heterogeneity in breast cancer groups and reduced functional genes and pathways. Conclusion Compared to the general population, breast cancer patients exhibited a distinct dysbiosis in their gut microbiota. Further investigation is warranted to determine if this dysbiotic state, linked to a predicted downregulation of functional pathways critical for homeostasis, plays a role in breast cancer development.
Yamada et al. (2025) studied this question.