the nose knows?

A study published in the British Medical Journal suggests dogs can sniff out bladder cancer in people.i really surprise after read it.i really want to know how a dog can do this?unbelievable!!!the article didn't mention about it so i don't know how a dog can do this.maybe dog has a sensitive nose that can recognise all the thing.corp also need the help of dog to find out the drug.RD Pet,Aug 2007,page140.i enjoy read it because it really outstanding compare to other article inside the book.