You gotta be kidding.... One of my old consultants was a bu88er for trying to squeeze as much as possible on a list and always wanting extra lists, he hated cancelling! (Mainly because he had such a long waiting list but I suspect there was a large element of avoiding his paperwork thrown in there as well). IThere may be some surgeons will say cancel at the drop of a hat (I've not met any), others, depending on what you're having done, just won't operate because of other risk factors involved and so the patient may as well be spared the journey where possible if the answer is already a given.
It's not good patient care to drag someone in when there's really no reason for them to be there, I'd be pretty cross if it was me.