I dont know about them coming back ten times worse, really..................
My Sass had cancer, ad still gets it from time to time.
We were told that as long as they keep growing on the outside where you can see them, where they are easily removed, this is a good sign.
Im dont know exactly how your daisys is growing, but at that age, it seems as if it were removed and treated, yes it may come back, because it is in her, but ten times worse, I seriously dont beleive that.
But Im no vet either!
Id go with the flow, until it got too bad.
Good luck, our thoughts are with you all.