Sure it's good for you. But it's not a magical cure and people who die from cancer aren't all at fault for not doing enough or not having the "right" attitude. My best friend's husband just died of pancreatic cancer, and I have never known anyone with a more positive attitude, or in better shape. I expect that was the point they were trying to make.
"My predominant feeling is one of gratitude. I have loved and been loved;I have been given much and I have given something in return...Above all, I have been a sentient being, a thinking animal, on this beautiful planet, and that in itself has been an enormous privilege and an adventure." O. Sacks