While no one will disagree that Cancer is a disease of pure evil, it is certainly not alone in that category.
My mother had breast cancer in 1969 which forced her to undergo a radical double mastectomy. She survived another 24 years afterward until she contracted Alzheimer's in mid-1993. After a 7 year struggle, it took her from us in late 2000. The pain it caused during that time was immense, and her eventual death was but a relief from the pain it had caused her and us.
Yes, Cancer is horrible because it can rapidly spread throughout the body and kill a person in a matter of months. Alzheimer's though is pure, unadulterated torture for the patient, family and caregivers alike. It is absolutely heartbreaking to see the person who raised you laying in bed and not even knowing who you are.
My prayers go out to all who suffer from these awful diseases as well as those who must sit silently by and watch it happen.