These definitions of words commonly misused here -- which scare the begeebers out of folks who don't know their actual meanings -- are combined ones from medical, veterinary, and biology dictionaries, but emphases are mine -- suited to common misunderstandings in ferret lists. If you follow the directions in the FML header you will be able to search in the archives on "FHL" or on "golden oldie" till you find a post that vet Bruce Williams wrote than explains why a very large number of the things non-vets call "cancer" are not cancer ( most adrenal growths, insulinomae ), why a growth type reappearing in the same tissue is not metastasis, etc. If you search both very recently and much further back in Bruce Williams posts in the FML archives you will find ones about why vets who are not used to ferrets assume that mast cell tumors must be bad news in them just as they too often are in dogs when actually it's typically the opposite for ferrets -- with (at that point for the old post) only one mast cell tumor ever known from a ferret that was malignant rather than benign. (I do not know if any further ones have been confirmed by pathology since then, but do know that vets who don't know ferrets still regularly just assume they are dangerous instead of learning more.) Important Note: some more recent dictionaries don't even include the term "cancer", and I have heard vets who won't use it due to the widespread confusion out there, and even some vets who won't use "tumor" due to too many assuming that any tumor is malignant. Tumor: ANY abnormal mass resulting from the excessive multiplication of cells; a swelling, especially that resulting from the growth of new tissue; a neoplasm cancer: Any MALIGNANT TUMOR; carcinoma; a carcinoma or sarcoma malignant: pertaining to or denoting progressive growth of CERTAIN TUMORS which if not checked by treatment SPREAD TO *DISTANT* SITES, terminating in death; a tendency to progress in virulence, cancer is the best known example benign: not malignant, as in CERTAIN TUMORS; not recurrent, favorable for recovery neoplasm: a tumor; any new growth, specifically one in which cell multiplication is uncontrolled and progressive, neoplasms may be benign or malignant (Subsets from Saunders: neoplasm, benign: a neoplasm having none of the characteristics of a malignant neoplasm (see below), i.e.it grows SLOWLY, expands WITHOUT METASTASIS, and USUALLY does not reoccur, though some types may reoccur in the same tissue neoplasm, malignant: a neoplasm with the characteristics of anaplasia, invasiveness and metastasis There are several other subsets of neoplasia in this dictionary but which I will not include here. metastasis: the transfer or disease from one organ or part to another NOT DIRECTLY CONNECTED WITH IT anaplasia: loss of differentiation of cells Those who have the _Saunder's Comprehensive Veterinary Dictionary_ will find that this resource often provides details beyond these bare-bones descriptions, (though certainly there also will be nuances in practise that those of us who are not medical professionals simply won't understand). It is a marvelous resource; I love it. If I had a rating for refs around here it would be among the best buys. It's better than any of my other medical dictionaries, even for sorting through things too technical for me in the _PDR_ books on herbs and on supplements that i have at home. Marvelous book: clearly written and very inclusive; more than worth what it cost. http://www.wbsaunders.com [Posted in FML issue 3694]