Well crap, I am so very sorry, this makes my heart sink
In any cancer dog with a history of tick disease, i would treat aggressively with doxy, since there seems to be a relationship between chronic underlying infection and cancer. PLUS, doxy itself has a couple of different anti-cancer properties.
There is a weak connection between the lyme vaccine and certain tumors. Weak in the sense it was mentioned by a vet at a teaching university and then I could never track any details after that.
Anyway, this dog: http://cinnamondog.com/
had a tumor similar to what you are describing, I think. Sander the Sheltie did suffer from lyme vaccine damage. No definitive proof they are related, but speculation.
Regardless of cause though, Sander was treated holistically and lived with that mouth tumor for many many years and died of old age (liver). If you have quetions, you can email via that site.
I like tumeric a lot, but there are a couple curcumin products that might be better absorbed. I'm a big fan of IP6 (enzymatic therapy, cell forte brand). Proteolytic enzymes too, like wobenzym or the like.
This really really sucks.