You can find some comprehensive data related to raw diets & pathogens in the June 2010 newsletter at http://www.b-naturals.com and the July 2010 issue of Whole Dog Journal. Most instances of pathogen related dog food contamination has actually been in kibble.

If you feed commercial raw, Stella & Chewy's batch tests all of their products.

Dehydrated raw is no different than fresh, as far as pathogen risk. 

I don't want to tell you what to do, but why don't you read the research about pathogens & kibble before deciding?

If your dog has been on a raw diet for so long, you should probably consider what effect the change will have on his digestive system, at a time it is already likely to be compromised.

Grain free kibble is not the same as raw & has a significant carbohydrate load…another consideration with cancer.

If you truly are worried about pathogens, feeding raw 50% of the time really wouldn't alter the risk. 

I am obviously a raw feeder & biased, but the next thing I would look at would be home cooked, (it can be time consuming). The b-naturals site has excellent home cooking instructions.

Do you have an option other than Bravo?

I did not read the reference, but that only makes sense if you are feeding an intact piece of boneless beef, which is not an option for long term feeding. The protein source should be rotated and bone, as well as organ meat included. Cooking any portion of it, defeats the purpose of raw feeding. You should never feed cooked bone, a vital component of a raw diet. You should never cook (or even thaw in a microwave) any commercially prepared raw food. It contains ground bones.

Honest Kitchen is a non heat processed, dehydrated raw food. Some formulas have a high carb content. Some are designed to be combined with raw protein. It's a quality product, just no different than raw for the purpose of this discussion.

Particularly because of the hype surrounding pathogen risk ( not necessarily based on science or fact) most commercial raw food producers routinely test their products. Stella & Chewy's as an example, batch tests. You do need to be more careful of your source if you are not feeding commercial, but that's true chemotherapy or not. Again, check the recall data on the incidence of salmonella and kibble.

Traditional vets often are very anti-raw feeding in general. This can be for a variety of reasons. They receive little nutritional training, outside the mainstream, some can ve very influenced by the pet food industry. Do you have access to an Alternative or Integrative vet you can consult?

Make whatever decision you are comfortable with. Just be sure it's based on fact, not fear or lack of information. As Jerry said, it may come down to your comfort level, disregarding the oncologist's advice.

I apologize, for saying it is a non heat process. Traditionally, the only way to truly eliminate pathogens with steam is at higher temperatures & a vacuum process. 

Honest kitchen is a quality product, with excellent controls, but the pathogen risk is likely equal to any commercial raw food and probably less than many kibbles.