Dan,
I had the same problem with cisplatin. My kidney function was compromised and I was already a kidney transplant patient. So, to preserve the only kidney I had, docs switched it to Carboplatin. From what I know, both are platinum drugs and are quite effective. For lung and ovarian cancers, they have already started replacing cisplatin with carboplatin , but for TCC, it is still not fully proven. I had 2 cycles of cisplatin & Gemzar, followed by 2 cycles of carboplatin & gemzar. Since you already had 3 cycles with cisplatin, I think the docs made the right decision and nothing should be compromised.Hope this helps.
-Shoba
S R
Kidney Transplant 1998
Upper Tract TCC, Dec 2004
Native kidney Right Nephroureterctomy Dec 2004
Non invasive bladder cancer,High Grade, Ta,TURB Jan 2012
Native kidney Left Nephroureterectomy Feb 2012