In order to keep my sanity, I have been spending hours and hours doing internet research and I have learned that one of the big risk factors for advanced prostate cancer is being exposed to Agent Orange between approximately 1969 and 1975. Which Marshall was.
So further research shows that he is entitled to money from the VA for having gotten this cancer. That is not much of a consolation, but it could amount to a nice monthly check. So he is going to contact the local VA rep and get that paperwork started. Every little bit will help.