A review examines the role of gut microbiota in patients with breast cancer and obesity, and how dysbiosis and the metabolic dysfunction associated with obesity interact in tumour progression. The work organises the proposed mechanisms and the possible interventions targeting this axis.
What was already known
Breast cancer remains a major global health concern: it accounts for 11.7% of all cancer cases and ranks as the second leading cause of female cancer-related deaths worldwide. Increasing evidence highlights the interplay between gut microbiota dysbiosis and obesity-associated metabolic dysfunction in breast cancer progression.
What this work adds
This is a review based on a systematic literature search in the PubMed and Web of Science databases for publications between July 2015 and January 2025. Search terms combined breast cancer, gut microbiota, obesity, dysbiosis, immunity and microbiome. Article selection prioritised studies on microbial alterations in breast cancer patients, mechanistic links between obesity and cancer progression, and microbiota-targeted interventions, including both original studies and authoritative reviews, supplemented by manual reference screening.
Main results
The review suggests that obesity may trigger systemic inflammation, altered adipokine secretion and disrupted steroid hormone metabolism via gut-derived β-glucuronidase activity, thereby exacerbating breast cancer onset and recurrence. Dysbiosis-driven metabolites such as branched-chain amino acids (BCAAs) and short-chain fatty acids (SCFAs) can activate oncogenic signalling pathways and immunosuppressive myeloid-derived suppressor cells, fostering tumour immune evasion. Conversely, dietary interventions, probiotics and faecal microbiota transplantation can alleviate dysbiosis, strengthen the gut barrier and restore anti-tumour immunity, improving chemotherapy response and reducing recurrence.
What it means
The authors conclude that future longitudinal studies are needed to clarify causal relationships, validate microbial biomarkers and translate preclinical findings into clinical application, and that addressing the gut-breast axis may offer transformative potential for precision oncology in obesity-driven breast cancer. Challenges remain, such as deciphering subtype-related microbial signatures and optimising microbiota-targeted therapies. These are research proposals; they do not constitute individualised supplementation or dietary recommendations.
Reference: Zhang H, Wang Y, Ning B, Wang Y, Sun T, Xu J. The gut microbiota-obesity axis in the pathogenesis and prognosis of breast cancer. Annals of Medicine, 2026. DOI/link
