I'm so sorry that you're going through this difficult time. I know that whatever decision you decide to make that it'll be what's best for Duke. I'm also going through something similar with my cat Sunny. He also has an aggressive type of cancer and only has 3-5 months to live. I've decided to just make him as comfortable as possible and enjoy the time that I have left with him. Another PT'er said that "sometimes the treatment is far worse than the disease itself." I believe this to be true and when the quality of life is gone then it's time to say goodbye. Lots of prayers an positive thoughts are being sent Duke's way. Please take care. (((HUGS)))