Risse, welcome. Please read Christine's post carefully. All the advice there is great. It's hard for me to imagine anyone with an M.D. after their name not urging any patient to quit smoking, whether they have cancer or not. I know how difficult it can be, having lost someone close to me from cancer a year ago who kept smoking even after surgery to remove half a lung, and through a couple of years of chemo.
Let us know how we can help, and please keep posting.
My best thoughts to you and your mother.