@danuta, that is a very good question that I would discuss with your oncologist. If it were me, I would go to a reputable website and compare the 2 different drug combinations. I would find out
- how they are administered
- what are the most common side effects

For example here are 2 pages from Macmillan Cancer Support:
- GemCarbo chemotherapy https://www.macmillan.org.uk/cancer-information-and-support/treatments-and-drugs/gemcarbo
- Paclitaxel and carboplatin https://www.macmillan.org.uk/cancer-information-and-support/treatments-and-drugs/paclitaxel-and-carboplatin

I would consider which side effects I would more likely be able to handle. Equipped with that information, I would ask loads of questions like:
- Which treatment has shown to be most effective with ureteral cancer?
- What characteristic of my cancer and personal medical history make one treatment preferable over the other?
- If I were to get XXX side effect, how can it be managed?

Did you ask the new oncologist why they chose carboplatin + paclitaxel rather than GemCarbo? How are you feeling after the chemo break?