When Harry was diagnosed with Cancer... I spent hours researching holistic type treatments online. There are about 4 promising options out there. Mushrooms derived supplements("K9 Immunity" is the brand name---the people there are very, very nice and even sent me free supplements to try on Harry. I exchanged lots of emails with Dorla who owns the main distribution outlet online and she was amazing). The 2nd out there that seems somewhat promising is Arteminisin. There is an entire online community on Yahoo I believe that is dedicated to it. I believe the research is primarily being done at the Univ of Washington(or Wash State maybe). Inositol(Univ of Maryland--the Dr who is doing a lot of the work actually responded to my email directly... and the 4th I would say would be Curcumin.
Best of luck. It took me hours and hours to kind of weed thru everything out there. But after it all, I'd have to say the above 4 options/combination of options seemed to come up the most. I am in no way connected to any of this stuff and everyone has to decide on their own how far to go. I just knew I wanted to try something as long as it didn't cause Harry any additional suffering.
Also, I would also recommend the Dog Cancer Guide(I think that's the name) by Dr Dressler. It kind of walks you through a lot of this stuff.
Prayers with Roscoe. Cancer is evil. It took the love of my life over a year ago.