Weiss L
Am J Pathol. 1979 Dec;97(3):601-8.
Consideration of the entire metastatic process reveals it to be very inefficient in terms of cancer cells. Of the millions of cells released from primary cancers, relatively few metastases result. This disparity implies that in some way the process is selective. Some evidence will be reviewed that indicates that cancer cells in metastases are in some way different from those in the primary cancer from which they arose. Primary cancers and their metastases, then, should possibly be regarded as distinct entities when one is considering therapy or seeking an understanding of the fundamental aspects of metastasis. In this presentation some nonexclusive mechanisms will be discussed that could be responsible for differences between primary and secondary cancers. These include: 1) Random (statistical) selection of metastasis-forming cells; 2) The existence of genotypic metastatic subpopulations; 3) The existence of transient metastatic "compartments" within primary cancer; 4) Site-induced changes (modulation) occurring in the metastasizing cells after they arrive in the target organ; 5) A combination of the above.
对整个转移过程的研究表明，就癌细胞而言，这一过程效率极低。在原发癌释放的数百万个细胞中，形成转移灶的相对较少。这种差异意味着该过程在某种程度上具有选择性。将回顾一些证据，这些证据表明转移灶中的癌细胞在某些方面与产生它们的原发癌中的癌细胞不同。因此，在考虑治疗方法或试图理解转移的基本方面时，原发癌及其转移灶可能应被视为不同的实体。在本报告中，将讨论一些并非相互排斥的机制，这些机制可能导致原发癌和继发癌之间的差异。这些机制包括：1）形成转移的细胞的随机（统计学）选择；2）基因型转移亚群的存在；3）原发癌内存在短暂的转移“隔室”；4）转移细胞到达靶器官后发生的部位诱导变化（调节）；5）上述各项的组合。
