癌症难治是由于恶性细胞能够侵袭和转移,转移过程包括一系列相关的前后步骤。原发癌要转移并生长,恶性细胞必须侵袭宿主的局部组织,进入血流并在其中存活,然后进入靶器官并形成转移灶。在癌症侵袭与转移过程中,必须降解一系列的天然组织屏障,其中包括基底膜和间质连接组织。基底膜是连续的细胞外结构,它将器官的实质与基质分开,是癌细胞要侵袭必须通过的第一道屏障。在侵袭与转移中,恶性细胞至 Cancer is refractory because malignant cells can invade and metastasize. The metastatic process involves a series of related steps. To metastasize and grow the primary cancer, the malignant cells must invade the host’s local tissue, enter the bloodstream and survive in it, then enter the target organ and form metastases. In the process of cancer invasion and metastasis, a series of natural tissue barriers must be degraded, including basement membrane and interstitial connective tissue. The basement membrane is a continuous extracellular structure that separates the substance of the organ from the matrix, and is the first barrier that cancer cells must pass through. In invasion and metastasis, malignant cells up to