Paul R. is facing the same dilemma and has a fairly well detailed thread on your question. It is in the "Coping, Anger and Fear" forum, thread titled "Refused Treatment".

There are no ways to sugarcoat this - death by oral cancer is an ugly and protracted death. (not that ANY cancer death isn't). You way wish to read Rosies blog about her experience with Heather, her 28 year old daughter. Also look for Danny Boys blog in the same topic. Amy also chronicles her stuggle in a very powerful way. Read Cookey's (Liz in the UK) thread "Walking Towards the Light".

If she chooses to go this route they may still give her some kind of treatment for palliative care to lessen the pain or really nasty side effects or symptoms.

Being a former caregiver for a dying parent I can echo what Amy has to say about your life being changed forever. I saw my own death there and it was a very dark period in my life.

Death is the most powerful teacher that there is. Get all of the support that you can.

Do a Google search for "end of life" and you will find valuable links to information that may help you.