乳腺癌是女性中最常见、最异质的癌症。此外，乳腺癌转移到远处器官（例如脑、肺和骨骼）的几率很高。乳腺癌骨转移患者的总体生存率和无复发生存率较差。此外，化疗和免疫疗法对于预防或减少癌症转移无效。肠道和乳房中存在的微生物，称为常驻微生物组，对乳腺癌的形成和进展具有重要影响。最近的研究发现一些微生物会诱导乳腺癌骨转移。这些生物体利用多种机制，包括诱导上皮间质转化、类固醇激素代谢、免疫修饰、骨重塑以及改变肿瘤微环境并增强乳腺癌细胞转移倾向的微生物产物的分泌。然而，它们的参与使得这些微生物适合作为新的治疗靶点。因此，正在进行研究，使用化疗或免疫治疗药物，以及益生菌、抗生素或粪便微生物移植来预防和减少乳腺癌向远处器官（包括骨骼）的转移。本综述描述了肠道和乳腺微生物群与骨转移的关联。我们详细阐述了乳腺和肠道微生物群利用诱导乳腺癌转移（尤其是骨转移）的机制。该综述还强调了当前可能针对微生物组来预防或减少乳腺癌转移的治疗方案。最后，我们明确了维持肠道微生物群多样化的必要性，以防止生态失调，否则可能会诱发乳腺癌和转移，尤其是骨转移。该综述可能有助于对这些微生物组与骨转移之间的因果关系进行更详细的调查。此外，综述中描述的潜在治疗方案可能会促进针对肠道和乳腺微生物组来提高乳腺癌患者生存率的讨论和研究。© 2024 作者。由 Wiley periodicals LLC 出版的癌症报告。

Breast cancer is the most predominant and heterogeneous cancer in women. Moreover, breast cancer has a high prevalence to metastasize to distant organs, such as the brain, lungs, and bones. Patients with breast cancer metastasis to the bones have poor overall and relapse-free survival. Moreover, treatment using chemotherapy and immunotherapy is ineffective in preventing or reducing cancer metastasis.Microorganisms residing in the gut and breast, termed as the resident microbiome, have a significant influence on the formation and progression of breast cancer. Recent studies have identified some microorganisms that induce breast cancer metastasis to the bone. These organisms utilize multiple mechanisms, including induction of epithelial-mesenchymal transition, steroid hormone metabolism, immune modification, bone remodeling, and secretion of microbial products that alter tumor microenvironment, and enhance propensity of breast cancer cells to metastasize. However, their involvement makes these microorganisms suitable as novel therapeutic targets. Thus, studies are underway to prevent and reduce breast cancer metastasis to distant organs, including the bone, using chemotherapeutic or immunotherapeutic drugs, along with probiotics, antibiotics or fecal microbiota transplantation.The present review describes association of gut and breast microbiomes with bone metastases. We have elaborated on the mechanisms utilized by breast and gut microbiomes that induce breast cancer metastasis, especially to the bone. The review also highlights the current treatment options that may target both the microbiomes for preventing or reducing breast cancer metastases. Finally, we have specified the necessity of maintaining a diverse gut microbiome to prevent dysbiosis, which otherwise may induce breast carcinogenesis and metastasis especially to the bone. The review may facilitate more detailed investigations of the causal associations between these microbiomes and bone metastases. Moreover, the potential treatment options described in the review may promote discussions and research on the modes to improve survival of patients with breast cancer by targeting the gut and breast microbiomes.© 2024 The Author(s). Cancer Reports published by Wiley Periodicals LLC.