translation.en: Cancer cells mutate, and they gain the ability to release lots of those angiogenic factors, natural fertilizer, that tip the balance in favor of blood vessels invading the cancer.
translation.zh: 癌细胞通过变异 学会了释放 多种血管生长因子，也就是我们提到的天然肥料， 来引导平衡倾向血管生长， 然后长入肿瘤。