Webster's New World Medical Dictionary

biologic evolution
A process mediated by genes
that shows a slow rate of change and uses mutations
and selection as agents of change. New variants in
biologic evolution are often harmful, and when these
new variants are transmitted from parents to off-
spring, this occurs according to classical genetics.
Humans require cultural as well as biological evolu-
tion. See also 
cultural evolution.
biological response modifier
A substance that
stimulates the body’s response to infection and dis-
ease. Abbreviated BRM. The body naturally pro-
duces small amounts of certain BRMs. Some BRMs
are made in the laboratory in large amounts for use
in treating cancer, rheumatoid arthritis, Crohn’s dis-
ease, hepatitis, and other diseases. BRMs used in
biological therapy include monoclonal antibodies,
interferon, interleukin-2 (IL-2), and colony-stimu-
lating factor. Also known as biologics.
biological therapy
Treatment to stimulate or
restore the ability of the immune system to fight infec-
tion and disease. Biological therapy is thus any form
of treatment that uses the body’s natural abilities to
cause the immune system to fight infection, treat dis-
ease, or to protect the body from side effects of treat-
ment. For example, biological therapy to block the
action of a messenger of inflammation, called tumor
necrosis factor (TNF), is being used to treat condi-
tions such as Crohn’s disease and rheumatoid arthri-
tis. Also known as biotherapy or immunotherapy. See
also 
biological response modifier.
biomarker
A biologic feature that can be used to
measure the presence or progress of disease or the
effects of treatment. For example, prostate specific
antigen (PSA) is a biomarker for cancer of the
prostate.
biopsy
The removal of a sample of tissue for
examination under a microscope to check for can-
cer cells or other abnormalities.