In the context of this article, no, I don't have to wonder. He expresses very well why he doesn't want to entertain such longshots.
That point-blank saved his life. The cancer was gone within 4 months; he's been cancer free for 5 years. His younger brother was not so lucky, lung cancer (heavy smoker), he didn't last long after diagnosis.
Anyway, the OP isn't looking for miracles, he's preparing for his departure, in a beautiful and dignified manner -- totally respect the choice, but longshots are not the same odds they used to be wrt to cancer treatments, even stage 4.