The gut microbiota-obesity axis in the pathogenesis and prognosis of breast cancer.

In 30 seconds

This systematic review examined evidence on how gut microbiota and obesity may interact in breast cancer (BC), drawing on literature published from July 2015 to January 2025. It describes potential links through systemic inflammation, adipokine and steroid-hormone changes, microbial metabolites, and immune suppression. The review also discusses dietary interventions, probiotics, and fecal microbiota transplantation as possible ways to modify dysbiosis and influence treatment response or recurrence. No pooled effect estimate or single quantitative clinical outcome is reported; the authors emphasize that causal relationships and clinical applications remain to be established.

Key findings

• Obesity-associated dysbiosis may promote BC through inflammation, altered adipokines and steroid metabolism, and immune pathways.
• Microbial metabolites, including branched-chain amino acids and short-chain fatty acids, are described as potentially activating oncogenic signaling and immunosuppressive cells.
• Dietary interventions, probiotics, and fecal microbiota transplantation may improve gut-barrier function and antitumour immunity, with possible effects on chemotherapy response and recurrence.

Why it matters

The review brings together plausible gut–breast and obesity-related mechanisms that may help explain variation in BC progression and treatment response. It also highlights microbiota as a potential source of biomarkers or therapeutic targets. However, the evidence summarized does not establish that modifying the microbiota improves clinical outcomes, so these mechanisms should be viewed as research directions rather than proven clinical strategies.

What to keep in mind

The review identifies unresolved causal relationships, uncertainty about subtype-specific microbial signatures, and the need to translate preclinical findings into clinical applications.