Healing vibes for your kitty DH. I hope that your vet did, indeed, get all the cancerous cells during the surgery.

I wouldn't make any sudden decisions regarding amputation.

My Tioga (chow mix) was diagnosed with oral melanoma 4 years ago when she was 10. Everything I read on the internet said she'd be dead in a year. Luckily, I caught it when it was very small and the vet had managed to remove the whole damn thing. It's never been an issue since.

About two years ago I noticed a weird (almost certainly non-cancerous) gum growth on her canine. Vet referred me to a specialist who was ready to remove a chunk of her upper mandible (and relieve me of $4K) right then and there. I never went back to that vet & just took a wait and see approach and the weird growth hasn't gotten any bigger.

I did switch Tioga to a limited ingredient diet (Wellness Simple Food Solutions) on the recommendation of my vet.