Triple negative breast cancer. Of case?

My mother was diagnosed with breast cancer in November2017. According to histopathology report it is TNBC and doctor has not removed 1.8*3cm of tumour since it was Attached to blood vessel. After surgery she has undergone 4 cycles of chemo since December 2017 followed by 12 cycles of paclitaxel which was ended in June 2017. From April 2017, the area where surgery was done started swelling. Doctors were saying it happens. It is normal. But after the paclitaxel she has undergone a PET scan again which showed that she has a tumour of size 10*12cm. After that she has undergone 3 cycles of different chemo(some carbo chemo) to check if tumour shrinks. But it didn't shrink to doctor's expectation. He suggested another PET scan to check if the tumour is away from blood vessels. If so it can be operated and removed. I am worried. I have seen many people who were cured from breast cancer(at least for few years). Why my mother is suffering this much. Is there any solution for this type of case?