"Most of the patients that I have helped have not been people that I've seen. They've written to me, and I treasure those letters. I keep every one of them, because that puts it on a very personal relationship for me. And every time I talk at a meeting or seminar, somebody always comes up and says, my child had leukemia and is now cured, or I have a transplant. I mean, it seems to me that it's so widespread, it really affects me to know how many people have really been impacted."