He had a very treatable cancer that was found in the early stages and was given an excellent prognosis, but in his infinite megalomaniac manner he decided he knew better than the doctors and opted to treat his cancer at home with homeopathic remedies. His home made new age “cures” clearly didn’t work and by the time he finally decided to get proper treatment his cancer had metastasized and he was beyond help… sounds to me like he played a large hand in his own demise so the joke plays.