My previous dog had a nerve sheath tumor from a vaccine related site. Removed tumor, pathologist said it was cancer, did radiation (lots of money for that $6,000.00), should have just removed her leg and avoided all the pain and still had to remove leg anyway. She survived cancer and ended up with kidney problems - probably from a lifetime of adulterated, low nutritional (even though co. stated it was top of the line food) pet food. Found out if you do the radiation route pet needs high protein food in order to heal the site where radiation is done. Remember radiation is the equivalent of 2nd degree burns to the skin. Other option is to feed the pet as healthy, organic, grain free diet as possible and skip the cancer treatments. So that is route I took and current dog is fed organic, wholesome, home cooked food. Hope all works out well for your mom's cat and for her too.

ChelseaSkye, I am sorry to hear of the diagnosis... I know how frustrating and scary it is to read life expectancy statistics after a diagnosis!!  Have you ever considered Natural Cellular Defense?  Its Zeolite in liquid form...  it helps with cancer if used in high doses.  It is quite spendy though. 

Thanks for all your responses, I've been forwarding them all to my mother who has been struggling with treatment decisions.  The vaccination location appears to have been the rabies site and my mom lives in the Seattle area.  Thanks again.  Please keep your comments coming.