There are two new drugs recently approved to treat advanced kidney cancer, Nexavar and Sutent. In my opinion, they are too new to tell how long they'll work for. The older treatment is high dose Interleukin-2, which is a difficult treatment to tolerate, but can produce lasting remissions in the 15-20% who respond.
There is an email support list called KIDNEY-ONC specific to kidney cancer. See
http://cancerguide.org/kofaq/ to join.
A person with kidney cancer that has spread outside the kidney needs an oncologist with experience in treating kidney cancer. This cancer does not respond to conventional chemo or radiation, and it is rare enough that many oncologists haven't had experience in treating it.
Ask the Kidney Cancer Association (800.850.9132) for the name of an oncologist near you who has experience in treating kidney cancer, or join the KIDNEY-ONC support list and ask there.