As you have already realized she needs a vet immediately and you may have
to travel.  You will find vet listings or links to vet listings in:
 
http://www.ferretcongress.org
http://www.smartgroups.com/vault/ferrethealth/ReferenceShelf/FerretVets.htm
http://fhl.sonic-weasel.org/vets/   Search by zip code, read FAQ first.
http://www.quincyweb.net/quincy/vet.html
http://www.miamiferret.org/fhc/vets.htm
http://www.ferretcentral.org/for-others/db-vets.html
http://www.geocities.com/houseferrets13uk/Vets.html UK vets
http://www.ferrets.org/Veterinarian_Listings.htm   British Columbia vets
http://www.ferretnews.org/clinic.html         California
http://www.ferretsanonymous.com/medical.html  California
http://www.ferretuniverse.com/index.html
http://www.supportourshelters.org
area ferret clubs, magazines, etc.
 
Sue.  since you don't know what type of malignancy it is ask your vet and
see the pathology report on the removed tissues for the prognosis.  The
various types of malignancies vary greatly in prognosis.  For example,
with lymphoma it is not at all unheard of for an elderly one to get over
a year with Prednisolone, but the same ferret with carcinoma might only
get a few months (though I know of one who is a vet's ferret and the
ferret has had a good 5 months with it, happily enjoying life with pain
control and other meds, and Ashling is still playing at about 2 and a
half months since she first almost died of carcinoma thanks to her meds).
[Posted in FML issue 4364]