Well,from what i have read on fighting cancer,many people claim to have beaten cancer through changing their diet(mainly throwing meat off the table,and replacing it with BIO vegies and fruits and of course,fish) you might want to do a little more research on that because i am not entirely sure about the exact menu but i guess it varies from person to person.
Now for the nerve damage.I recall Mercury being the ruler of the nervous system,so you might wanna look for herbal products aquired from mercurial plants (a list of them should be available in Junius's Practical Handbook Of Plant Alchemy).
Thats all i can offer for now
UPDATE:And before i forget it,no more sugar for your father.Doesnt matter if its white,black,brown,blue or purple,sugar is a 1st tier cancer factory