I recently lost my wife to colon cancer; she did not have an advance directive. When the doctor asked me what her wishes were I told him what she wanted, he also asked my wife and she said the same thing, although he was not confident she could make a clear decision. But I was her husband and she was also refusing to wear an oxygen mask. It would be easier on you if he does fill one out, or in case you are not there to voice his wishes. I found this webpage https://www.health.gov.au/health-topics/palliative-care/planning-your-palliative-care/advance-care-directive
... View more