Without the formation of new blood vessels , tumors cannot expand beyond a few cubic millimeters , and that the rate of tumor growth correlates with the formation of new blood vessels . neovascularization may also be a critical role of tumor metastasis since it enhances entry of tumor cells into the circulation . consequently , highly vascular tumors may have the potential to produce metastases at a higher rate than less angiogenic tumors 没有新生血管形成，肿瘤生长超不过几个立方毫米，并且肿瘤生长速度与血管新生程度有关。新生血管在肿瘤转移中也有重要作用，促进肿瘤细胞进入血液循环，血管生长丰富的肿瘤比缺乏血管生长的肿瘤更容易发生转移。因此抑制肿瘤组织的新生血管形成，从而抑制肿瘤生长和发生转移已成为肿瘤治疗的一个重要策略。
