In my opinion, I am only a patient as Kris and your dad, iam no doctor.
As a rule of thrumb,chemotherapy of the same will continue until"disease progress or intolerable side effects occur" that is included partial response (PD)and stable response(SD) of the tumor.((Ie: tumor getting small(=PD) or no change in the tumor=(SD).
For more info on drugs used in treating cancer,the following link will be of some value. And remember, one drug works miracle for one, it does not apply to every one. And be careful, some doctor would like you to join clinical studies he or she is involved, that adds another layer of concern if disease is PD or SD.
http://www.cholangiocarcinoma.org/punbb … 198#p57198
Please know that my personal opinion is not intended nor implied to be a substitute for professional medical advice. If provided, information are for educational purposes.Consult doctor is a MUST for changing of treatment plans.