Energy metabolism in Cancer cells
Two things...

Rapidly proliferating tissues (esp tumours) rewire their energy metabolism anyway to aerobic glycolysis where you have energy being produced by lactic acid fermentation even if oxygen is present. This is called the Warburg effect.Here's the thing about "low yield" though - glycolysis chucks out less ATP per reaction at the end, but you can crunch through a lot more ATP by just having more of it going on. 

Secondly, hypoxia in a tumour is generally rate limiting, and therefore the shunting away of alpha-KG with the consequence of increased angiogenesis is good for the tumour.