Hi organic
I'm afraid you'll only be awarded it if the people responsible for your care complete the form. You say that your consultant has said you have 12 months to live "if left untreated." As you are due to start the immunotherapy, and they hope it works - the nurse has given the reason why they can't currently complete the form. It's a clinical judgement. You can try and argue - but the DWP go with what the clinicians say. I truly hope they are right and you see an improvement in your condition.
BIS
Nothing on this board constitutes legal advice - always consult a professional about specific problems