Unveiling the Microbiota: A New Frontier in Breast Cancer Pathogenesis—A Single-Center Preliminary Study

Background: Breast cancer is the most common malignancy affecting women worldwide and continues to pose significant challenges despite progress in early detection and personalized therapies. While its pathogenesis has traditionally been associated with genetic, hormonal, and environmental factors, recent studies have highlighted the potential role of dysbiosis—an imbalance in gut and systemic microbiota—in breast cancer development and progression. This article aims to examine the mechanisms through which systemic dysbiosis may contribute to breast cancer risk and explore its therapeutic implications. Methods: This study seeks to analyze and compare the fecal microbiota profiles of breast cancer patients and healthy individuals from a single center in Craiova, Romania, in order to identify microbial signatures linked to breast cancer and BRCA mutation status. Special attention is given to the gut–liver axis and its influence on estrogen circulation, a key factor in hormone-sensitive breast cancers. Results: Evidence suggests that dysbiosis can influence breast cancer progression by promoting chronic inflammation, impairing immune regulation, and altering estrogen metabolism through the gut–liver axis. These effects may contribute to tumor development, immune evasion, and therapeutic resistance. Interventions aimed at restoring microbial balance show promise in preclinical studies for mitigating these effects. Conclusions: Systemic dysbiosis represents a potentially modifiable risk factor in breast cancer. Microbiota profiling may serve as a useful biomarker for risk stratification and therapeutic response. Future research into microbiome-based interventions could offer novel approaches for prevention and treatment in breast cancer care.