I think that the doctor is being quite honest with you. It sounds as if you have a 50/50 chance, statistically.
HOWEVER and it is a big HOWEVER
there is a lot more to it than statistics. The patient's attitude and will to fight this thing are very important, as is the will and strength of his support system, you!
This is a serious disease and you are doing everything you can to get the best outcome, starting with chemo.
Some doctors don't tell the patient everything; I am one of those who wants/needs to know exactly what is going on, so I respect a doctor who will tell me. You asked your questions, and he did not "blow you off" but answered them to the best of his knowledge.
We all wish you the very best, and are here for you.
We will be thinking the very best thoughts, and you should also. An optimistic attitude goes a long way now.
Sara Anne