Hello harrington...
No one can understand the pain of watching helplessly as a loved one is ravaged by cancer unless they have gone thru it themselves, ten years ago my family went thru this with our nephew who was only 26 years old and contracted spinal cancer, the doctors gave him six months and that is almost exactly how long he lasted.
The good book says that god works in mysterious ways, sometimes its hard to understand the reasons why, however, in the end the only thing we can do is take comfort in the thought that they are not suffering any more and are in a better place.
My wife and I will have you and yours in our prayers, take care and be well my friend...
DD