George,
I am truly sorry to hear of your brother's passing and how rough his last months after diagnosis were. You are right in that early detection is the best defense for most cancers. I agree with you that once the cancer is so far advanced, compromising the body by chemo/radiation, etc., probably doesn't help the body to fight the disease at that point.
Sometimes, it just doesn't make any sense, does it? Now that cancer has become the #1 killer of all people in this country 85 and under, you would think we would know more about it. Even as advanced as we are in the medical arena, so much is just hit and miss. Unfortunately, once it is too late, we can only guess what would have worked, had we done something different.
I took care of my mother 24 x 7 for almost a year, thinking I could direct her care and keep her around longer. In many ways, her 4 week "death sentence" as I call it, stretched out to 9 months or so. As I look back at it, was her quality of life worth what she had to endure? I left it totally up to her and told her that whatever her wishes were, I would be her warrior, I would be her comforter. I battled doctors, insurance companies, etc., as long as she wanted to. In the end, as I look back, I gave her everything she wanted at that stage of her life. It sounds like you, too, were there for Mark in any way he wanted.
Do not lose hope or faith on mankind, medicine and life over your brother's suffering. When we lose someone so dear to us, we tend to let our mind wander towards the what ifs of life. Had we just done this different or that different, it would have changed the outcome. There is only so much we can do and stuff just happens, for whatever reason. Some say it is God's will but I do not believe God wills someone to die or suffer. He merely promises us in this broken world that He will be by our side and carry us when we need it. It is His promise of the eternal life without pain and suffering after this life that we should all look forward to.
I pray He will comfort you and provide you with peace all the days of your life. Your brother was so blessed to have your love in his life.
Ed