Clinical and experimental studies demonstrate that VCO is a common strategy used by cancer cells to evade antiangiogenic therapies; “normalization” of the vasculature by bevacizumab eliminates immature tumor microvessels, retaining the mature ones, in response to anti-VEGF treatment the remaining blood vessels increase their diameter, a response that also enhances VCO in colorectal cancer cells already metastasized to the liver [114]. This evidence concerns the gene VEGFA and cancer.