As a contemporary of your father, I can well understand his reluctance to accept his frail condition. It may well be that he was coming to terms with his situation and didn’t realize just how little time he had. Or maybe, he was following up on his condition but since he was comfortable enough to work he didn’t feel a need to push the docs to see him right away. However, be comforted that he did work that final week. He got to go out doing what he wanted to do and living a full life. That, in itself, is a blessing that you may come to appreciate more and more as you reach his age.
Often times, health conditions can be genetic. Take care of yourself and make sure that your docs know what happened. There may be preventative steps that they can recommend that you and your offspring can take.
My heart felt condolences go out to you. Think fondly of him, he would have liked that.
Mike