Our server is having problems so I will just have to keep trying to send
this.  Treat it as an supporting document to Bruce William's excellent
post taken from FHL digest 348.  I especially liked his providing the
direct translation of "tumor" as "swelling", and his explanation that
not all growths which can metastasize do so readily.
 
These definitions are combined ones from medical, veterinary, and
biology dictionaries, but emphases are mine and i am willing to be
corrected if I blew it...
 
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
 
neoplasm, malignant: a neoplasm with the characteristics of anaplasia,
invasiveness and metastasis
 
There are several other subsets of neoplasia in this dictionary.
 
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.
[Posted in FML issue 3516]