Carr I, Orr F W
Can Med Assoc J. 1983 May 15;128(10):1164-7.
Malignant tumours cause sickness and death largely because they invade and metastasize. Such spread is made possible by many cellular properties, including the ability of neoplastic cells to move and to release degradative enzymes. These properties enable tumour cells to break free of the primary tumour, penetrate blood or lymphatic vessels and, after being transported to distant sites, pass out of the vessels to establish new tumours. Not all cells in a tumour, however, are able to metastasize, so the process tends to select for greater malignancy in the secondary tumour. The heterogeneity of tumours probably accounts for the difficulty of providing effective treatment, in that the various subpopulations of cells arising from each tumour vary in their responses to chemotherapeutic agents. We do not yet understand the process sufficiently to treat cancer patients by interfering selectively with the metastatic mechanisms.
恶性肿瘤导致疾病和死亡，主要是因为它们会侵袭和转移。肿瘤细胞的许多特性使得这种扩散成为可能，包括肿瘤细胞移动和释放降解酶的能力。这些特性使肿瘤细胞能够脱离原发肿瘤，穿透血管或淋巴管，并在被输送到远处部位后，穿出血管形成新的肿瘤。然而，肿瘤中的并非所有细胞都能够转移，因此这个过程往往会在继发性肿瘤中选择更具恶性的细胞。肿瘤的异质性可能是提供有效治疗存在困难的原因，因为每个肿瘤产生的各种细胞亚群对化疗药物的反应各不相同。我们对这个过程的了解还不够充分，无法通过选择性干扰转移机制来治疗癌症患者。
