Keep in mind that the drugs used to fight kidney cancer will attack all known & un-known tumors.
In my opinion, if you do not have visible (via Cat scan) tumors, that is good. Go after the cancer now & keep it that way.
So many of the stories here & on other web sites are basically the same. (including mine) Dr's don't see any tumors right now so it must be O/K. A couple of years later they find that the disease has spread & is now stage 4 with multiple mets. They couldn,t see them before because they were too small.
There is also a thing called remission, that I wonder about. Is the cancer really under control, or do the tumors just need a chance to grow larger so they can be identified.
May your decision work out perfectly.
Bill