Why do Cancer patients smell like death?

I know, I've had a similar experience in a close friends room about 3 days before he died. It's because a part of them is dying - they are rotting right before your eyes. Worse yet they are rotting from cancer and it smells horrible, and when it gets bad enough there isn't a damned thing they can do about the smell. Doubly horrible is the fact the poor girl you sat next to could smell it too, and knew exactly where the smell came from. Awful!!