乳腺癌在女性中最常见，在大多数情况下，没有扩散的证据，并且原发肿瘤被切除，从而实现“治愈”。然而，其中 10% 至 30% 的女性在数年至数十年后出现远处转移。这是由于乳腺癌细胞扩散到远处器官并处于静止状态。这称为转移休眠。休眠细胞通常对化疗、激素治疗和免疫治疗有抵抗力，因为它们不循环并从微环境接收生存信号。在这种状态下，它们在临床上是无关紧要的。然而，包括衰老和炎症在内的危险因素可能会唤醒休眠细胞并导致乳腺癌复发，这种情况甚至可能在原发肿瘤切除十多年后发生。这些乳腺癌细胞如何保持休眠状态正在被揭开。一个关键因素似乎是骨髓中的间充质干细胞，最近的研究已证明它可以促进乳腺癌转移休眠。进行间接共培养、直接共培养和外泌体提取来研究信号操作模式。多种信号分子在此过程中发挥作用，包括蛋白质因子和 microRNA。我们整合这些研究来总结该领域当前的发现和差距，并提出该领域未来的研究方向。

Breast cancer is most common in women, and in most cases there is no evidence of spread and the primary tumor is removed, resulting in a 'cure'. However, in 10% to 30% of these women, distant metastases recur after years to decades. This is due to breast cancer cells disseminating to distant organs and lying quiescent. This is called metastatic dormancy. Dormant cells are generally resistant to chemotherapy, hormone therapy and immunotherapy as they are non-cycling and receive survival signals from their microenvironment. In this state, they are clinically irrelevant. However, risk factors, including aging and inflammation can awaken dormant cells and cause breast cancer recurrences, which may happen even more than ten years after the primary tumor removal. How these breast cancer cells remain in dormancy is being unraveled. A key element appears to be the mesenchymal stem cells in the bone marrow that have been shown to promote breast cancer metastatic dormancy in recent studies. Indirect co-culture, direct co-culture and exosome extraction were conducted to investigate the modes of signal operation. Multiple signaling molecules act in this process including both protein factors and microRNAs. We integrate these studies to summarize current findings and gaps in the field and suggest future research directions for this field.