VEGFA and lung cancer: Second, malignant lung tumors have rich neovascularization due to the high expression of vascular endothelial growth factor, which may theoretically increase blood supply of tumor tissues (27); however, malignant tumors tend to have immature new blood vessels with increased microvascular permeability and relatively insufficient veins or lymphatic vessels to drain the excess leaking fluid, which may result in compression of tumoral vessels and lead to reduced blood perfusion in the tissues.