That is not a type of cancer I have worked with before. With his complex medical history I would highly recommend finding a holistic vet in your area to consult with. They are going to be able to better help and with cats it is even more important as I find that usually you only get 2-3 supplements before they start rejecting them.
http://pathwithpaws.com/blog/2011/12/11/how-to-find-a-good-holistic-vet-to-work-with
