Metastasis remains a major challenge in treating breast cancer. Breast tumors metastasize to organ-specific locations such as the brain, lungs, and bone, but why some organs are favored over others remains unclear. Breast tumors also show heterogeneity, plasticity, and distinct microenvironments. This contributes to treatment failure and relapse. The interaction of breast cancer cells with their metastatic microenvironment has led to the concept that primary breast cancer cells act as seeds, whereas the metastatic tissue microenvironment (TME) is the soil. Improving our understanding of this interaction could lead to better treatment strategies for metastatic breast cancer. Targeted treatments for different subtypes of breast cancers have improved overall patient survival, even with metastasis. However, these targeted treatments are based upon the biology of the primary tumor and often these patients’ relapse, after therapy, with metastatic tumors. The advent of immunotherapy allowed the immune system to target metastatic tumors. Unfortunately, immunotherapy has not been as effective in metastatic breast cancer relative to other cancers with metastases, such as melanoma. This review will describe the heterogeneic nature of breast cancer cells and their microenvironments. The distinct properties of metastatic breast cancer cells and their microenvironments that allow interactions, especially in bone and brain metastasis, will also be described. Finally, we will review immunotherapy approaches to treat metastatic breast tumors and discuss future therapeutic approaches to improve treatments for metastatic breast cancer.
转移仍是治疗乳腺癌的主要挑战。乳腺肿瘤会转移至脑、肺、骨等器官特异性部位，但为何某些器官更易受累尚不明确。乳腺肿瘤还具有异质性、可塑性及独特的微环境特征，这些因素共同导致治疗失败与复发。乳腺癌细胞与转移微环境的相互作用形成了"种子与土壤"理论：原发性乳腺癌细胞如同种子，而转移组织微环境则构成土壤。深化对此相互作用机制的理解，有望为转移性乳腺癌制定更优治疗策略。针对不同乳腺癌亚型的靶向治疗已提升患者总体生存率，即使发生转移亦然。然而，这些靶向治疗方案主要基于原发肿瘤的生物学特性，患者治疗后仍常出现转移性肿瘤复发。免疫疗法的出现使免疫系统能够靶向攻击转移性肿瘤，但相较于黑色素瘤等其他转移性癌症，免疫疗法在转移性乳腺癌中的疗效尚未达到同等水平。本综述将系统阐述乳腺癌细胞及其微环境的异质性特征，重点解析转移性乳腺癌细胞与微环境（尤其在骨转移和脑转移中）相互作用的独特生物学特性。最后，我们将评述当前治疗转移性乳腺肿瘤的免疫疗法策略，并探讨未来改善转移性乳腺癌治疗的新型治疗途径。
肿瘤(癌症)患者之家