Cat had several tests at University Vet School Thursday. All were clear. There was no other cancer detected in her body. She will start radiation next week.
Her oncologist says cats with this cancer treated with radiation have an average survival rate of 1 1/2 years of quality life. Some longer, some less.
The decision has been made. Thank you for all of your responses and good wishes. I agree that the person who loves the cat will know when its time has come. However, it can be a heart-wrenching wait.