Hi Tom's Son,
So sorry to hear how things went, but don't blame yourself or your family...we put our trust out there, we are not oncologists. I've been there so I know how you feel. I lost my sister to breast cancer, another sister got bladder cancer (she is doing very well!) then I got breast cancer too. I'm fine too, I learned a lot from my poor sister's disastrous experience...did things very differently and still here.
Gemzar is actually less toxic than Taxol or Carboplatin. The good thing is that all those drugs work for both breast and bladder cancer. Most breast cancer is HEr2 negative, but more aggressive cancers I'm sorry to say are HEr2 positive. Whichever cancer caused the liver mets, Herceptin is the drug of choice so your father's doctor sounds like he has learned something (if it is the same one who lost control of the situation in the first place). Zometa is pretty state of the art, as is Herceptin.
The rule of thumb is that once a person gets cancer their risk for developing a 2nd primary is bigger. We become cancer friendly environments, I guess. Horrible thought, I know.
I wish you and your family all the best,
Wendy