I treated my beautiful black Lab Tasha with chemo when she got lymphoma at age 9 (the lymph nodes were compressing her trachea, she was literally strangling). Cost about $4000.
She got a remission they said might last 2-5 years. It lasted four weeks, and I had to put her down.
Horrible experience. I would never do it again. Good luck with your dog, I know how much they mean to us.
Oh, and by the way - if you ever want to write a novel about dogs and their owners, spend six or seven afternoons in the waiting room of New England Veterinary Oncology or some other such place, to witness some amazing and heart-rending stories.
What really turned me away from the chemotherapy was that the remission would not last. Eventually the lymphoma would develop resistance to it and come raging back again. The oncologist told us there was no long-term cure for this disease, just short term remission through chemotherapy. Then we would have to relive what we are going through now all over again.