Just for the record, I didn't advocate only Dr. Budwig's diet for her dog. I simply provided the links to flesh out the information about it since it had already been given.
There are lots of good sites with tons of information concerning alternatives to chemo and/or radiation and/or other such toxic cancer "treatments." In the end, the best we can do is work with our vet, hopefully a holistic vet who's well trained in both allopathic and natural medicines, and educate ourselves in doing what is best for our furry, feathered, and finned family members.
While a google or similar search engine can turn up a lot of good information, sites like Shirleys Wellness Cafe are excellent places to start.
Since there is a major focus on alternative treatments and therapies here, the responses most likely will include various alternative suggestions. Despite your reservations, Dr. Budwig's diet has much success for many years.
I will not subject an animal to a treatment I would not take myself (aside, of course, of the neutering to help prevent unneccessary pregnancies and an escalation of the population when there are already so many thousands of sick and starving strays. I seriously doubt I could ever convince a cat to insist the tom wear a condom if they escaped while in heat. Years ago I had a dog on "the pill" but stopped when her hormones got severely out of whack. After research, neutering seems the least problematic and most humane. That said, I did have a tubal ligation at age 21.)
I have already informed my family I will not take chemo nor radiation therapy if I am ever diagnosed with cancer. Therefore, I, for one, would be willing to at least use whatever researched herbal or natural treatments that have been proven to work before in addition to what other, less toxic alternatives to chemo or radiation that my doctor or my vet may suggest.