I am sorry to hear your story. Both my parents died of cancer, and I am 55 with lung cancer (never smoked) and the simple answer is cancer does not discriminate. We still don't know why some get it and some dont. My cancer is curable (so they say) but I'm under no illusions, I am hugely more likely to get it again now. Yes somebody 84 should have been told, and if I got to that ripe old age I would swap, but cancer is a ***. All you can do is make your Dad's time left as happy as possible. I wish you and your dad well.

Sorry to hear that. 

My dad was healthy till they told him, surely it would have been best to spare him the news and tell us his family,

how can you make everything ok when everyday he thinks it could be his last?