Why has McCain refused to released his medical records?

John McCain has had every form of skin cancer. He's the oldest presidential candidate. No one knows his true medical health status. He keeps getting procedures done. Why are we talking about lipstick and not this? Why did his campaign give reporters 3 hours in a room with an edited version of his medical records with no way to document their findings? Why isn't this front page material? Why is the Obama campaign not airing ads about this?