My husband had a different cancer but we were in a similar situation. He had a clean PET after 3 of 6 but he continued on in the spirit of "making sure". This is what our wonderful oncologist planned and wanted and he was the man. PETs and CTs don't always read in black and white but mostly we didn't trust the *&%^%$ cancer. Mike was really sick going into the last one and the doctor told him he could stop but he wanted to finish the course. We kind of related it to taking antibiotics - you got to take all the pills even if you're feeling better. He got a lighter dose, they kept a close eye on him and he got through it.
I really didn't have a say but was in agreement. I've been coming to this site for a year and a half and read all the posts. Something I picked up on and would like to relate is - how horrible would it be if you stopped the chemo and then had a recurrence? It happens.
So that's our experience and some of my thoughts.
God bless you in your fight -
Cray