I think it is so complicated as cancer cells use hypoxia as metabolic adaptation so may be metabolic enzymes should be studied to study which one is overexpressed or downregulated to be used in target therapy
.please check this review http://www.nature.com/oncsis/journal/v5/n1/full/oncsis201550a.html
if it is in vivo supplementing VEGF- vascular endothelial growth factor would enhance angiogenesis and and supply more O2 to the region by formation of new blood capillaries but still the hypoxia would remain as it is created by the crushing and necrosis of proto-neoplasma aka old tumor cells by the newly forming cells as the tumor develops. so the solid tumor when treated with VEGF may retard Hypoxia but not completely convert it to normoxic conditions.