Hi there. I'm new to the forum and have great concern for my father.

My dad was diagnosed with bowel cancer last month. He took the news remarkably well and talks about chemotherapy and radiotherapy treatment were positive. He was due to travel to Southampton for five weeks of said treatments starting next month, but yesterday he declared to us (mum, brother, and I) that he no longer wants to go through with it. 

A little context that makes me understand his decision: he is 77 years old, double-incontinent, can hardly walk due to bad knees and old age, and has been saying for a while now (pre-diagnosis) that he is depressed and just wants to die. If I can try to put myself in his shoes for a moment, I can partly understand his decision - it's his life and his choice, plus he has close-to-zero quality of life at the moment, so I can sympathize with him to a degree. But on the other hand, it's extremely hard not to feel that he is being selfish and just giving up when there is still hope that he could get better. We're finding it incredibly difficult to accept his decision. 

My mother is obviously devastated and can't stop crying (they've been married 42 years) and I just don't know what to say to her. I have tried speaking to my father to get him to reconsider, but he just doesn't seem interested. I feel totally helpless. 

Any advice on what to do or how to accept his decision from anyone who has been through a similar situation would be greatly appreciated.