>Metastasis is the hallmark of malignancy. The worst tumors have the
>propensity to go anywhere and start growing (like lymphoma). However,
>we can recognize malignant tumors even before they metastasize, often
>by characteristic features seen under the microscope.
>
>Adrenal carcinomas (malignant adrenal tumors) are interesting
>neoplasms. Although they possess the ability to metastasize, only a
>small number do, and usually only late in the course of disease. It is
>likely that they do metastasize a lot, but have trouble gaining a
>foothold in distant tissues, so it takes a long time and many attempts
>if they ever truly metastasize.
>
>Insulinomas are generally not malignant tumors as they only very
>rarely metastasize. The presence of multiple tumors in the same organ
>over time is not metastasis. We do not understand the mechanism behind
>the generation of these tumors, and when we do surgery to remove them,
>we really are only treating the end point of this process, without
>address the cause. Thus it is really no surprise that the rate of
>recurrence is about 40% within 10 months.
>
>With kindest regards,
>Bruce Williams, DVM

AND:
>Treat this as an supporting document to Bruce William's excellent post
>above 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... ( In years and of running these past vets
>none have suggested changes.)
>
>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

[Posted in FML 7010]