Seekinganswers: Whilst you are quite correct that "the patient cannot decide what they want ", the gist of my argument was that the they can (and frequently do) decide and then dictate what they do not want and refuse to have it. This extends even to refusing a life-saving treatment. Nobody can force a patient to have any form of treatment against their wishes, as long as the patient is mentally competent and of the age of consent. If a competent patient refuses to have a particular treatment but is then forced to have it (or it is given by subterfuge), there would be a good case in law for an assault.
In the instance that a patient adamantly refuses to comply with the doctor's advice, the doctor may decline to treat that patient further but would then be well advised to get the appropriate legal documentation signed by the patient and properly witnessed so as to cover the doctor against any resulting liabilities. (He would also be well advised to find another doctor who was prepared to care for the patient.) If, however, the doctor is prepared to continue caring for the patient the circumstances should be legally noted together with the patient legally absolving the doctor from any liability consequent upon the "modified" care now being provided being considered sub-optimal according to current medical opinion.
Although I said in my original post, that I thought it "very unlikely" for a patient to be denied a new S.O.C. which included DCVax-L but minus the temozolomide, in fact I cannot honestly see how such a denial of treatment could possibly be sustained without a legal challenge and an appearance before a Judge. Even medical politicians have some degree of self-preservation and would hesitate putting such a case before a Judge with all the resultant public controversy. Better to just get on with what the patient wants and save the NHS £35+k on each case of GBM which is treated with DCVax-L and not treated with temozolomide - and perhaps increase the cure rate even further.