California Pacific Medical Center and Research Institute, San Francisco, CA, USA.
University of California, San Francisco, San Francisco, CA, USA.
Clin Exp Metastasis. 2022 Feb;39(1):139-157. doi: 10.1007/s10585-021-10123-w. Epub 2021 Oct 15.
The lymphatic system is a complicated system consisting of the lymphatic vessels and lymph nodes draining the extracellular fluid containing cellular debris, excess water and toxins to the circulatory system. The lymph nodes serve as a filter, thus, when the lymph fluid returns to the heart, it is completely sterile. In addition, the lymphatic system includes the mucosa-associated lymphoid tissue, such as tonsils, adenoids, Peyers patches in the small bowel and even the appendix. Taking advantage of the drainage system of the lymphatics, cancer cells enter the lymphatic vessels and then the lymph nodes. In general, the lymph nodes may serve as a gateway in the majority of cases in early cancer. Occasionally, the cancer cells may enter the blood vessels. This review article emphasizes the structural integrity of the lymphatic system through which cancer cells may spread. Using melanoma and breast cancer sentinel lymph node model systems, the spread of early cancer through the lymphatic system is progressive in a majority of cases. The lymphatic systems of the internal organs are much more complicated and difficult to study. Knowledge from melanoma and breast cancer spread to the sentinel lymph node may establish the basic principles of cancer metastasis. The goal of this review article is to emphasize the complexity of the lymphatic system. To date, the molecular mechanisms of cancer spread from the cancer microenvironment to the sentinel lymph node and distant sites are still poorly understood and their elucidation should take major priority in cancer metastasis research.
淋巴系统是一个复杂的系统，由淋巴管和淋巴结组成，它们将含有细胞碎片、多余水分和毒素的细胞外液引流到循环系统。淋巴结充当过滤器，因此，当淋巴液回流到心脏时，它是完全无菌的。此外，淋巴系统还包括黏膜相关淋巴组织，如扁桃体、腺样体、小肠中的派尔集合淋巴结，甚至阑尾。癌细胞利用淋巴管的引流系统进入淋巴管，然后进入淋巴结。一般来说，淋巴结在大多数早期癌症病例中可能充当一个门户。偶尔，癌细胞可能进入血管。本文综述强调了淋巴系统的结构完整性，癌细胞可能通过该系统扩散。利用黑色素瘤和乳腺癌前哨淋巴结模型系统，大多数情况下，早期癌症通过淋巴系统的扩散是渐进的。内脏器官的淋巴系统要复杂得多，也更难研究。从黑色素瘤和乳腺癌向前哨淋巴结转移的知识可能为癌症转移的基本原理奠定基础。本文综述的目的是强调淋巴系统的复杂性。迄今为止，癌症从肿瘤微环境扩散到前哨淋巴结和远处部位的分子机制仍知之甚少，阐明这些机制应成为癌症转移研究的首要重点。
