You know I don't find this wierd or miraculous. Cancer is a disease and our immune system battles cancer cells everyday. The issue is that cancer is our own cells, not a foreign body so if our immune system doesn't recognize it as a threat then it does nothing to stop it. If it does recognize it as a threat then it will fight and possibly irradicate the disease.

Is it likely once a life threatening tumor has developed no...has it happened before? I think so. This guy is a lucky b*st*rd and if I were him I'd be thanking my lucky stars.