| Biological Therapies in the Treatment of
Cancer
Biological therapy (sometimes called immunotherapy,) is a relatively
new addition to the family of cancer treatments. Biological therapies
use the body's immune system, either directly or indirectly, to
fight cancer or to lessen the side effects that may be caused
by some cancer treatments.
The immune system is a complex network of cells and organs that
work together to defend the body against attacks by "foreign,"
or "non-self," invaders. This network is one of the
body's main defenses against disease. It works against diseases
such as cancer. Cancer may develop when the immune system breaks
down or is not functioning adequately. Biological therapies are
designed to repair, stimulate, or enhance the immune system's
responses.
Immune system cells B cells, T cells, natural killer (NK) cells,
and monocyte. Cells in the immune system secrete two types of
proteins: antibodies and cytokines. Antibodies respond to antigens
by latching onto or binding with the antigens. Specific antibodies
match specific antigens, fitting together similarly the way a
key fits a lock. Cytokines are substances produced by some immune
system cells to communicate with other cells. Types of cytokines
include lymphokines, interferon, interleukins, and colony-stimulating
factors.
Biological therapies may be used to stop, control, or suppress
processes that permit cancer growth; make cancer cells more recognizable,
and therefore more susceptible to destruction by the immune system;
boost the killing power of immune system cells, such as T cells,
NK cells, and macrophages; alter cancer cells' growth patterns
to promote behavior like that of healthy cells; block or reverse
the process that changes a normal cell or a precancerous cell
into a cancerous cell; enhance the body's ability to repair or
replace normal cells damaged or destroyed by other forms of cancer
treatment such as chemotherapy or radiation, and prevent cancer
cells from spreading to other parts of the body. Some biological
therapies are being used alone or in combination with other treatments
such as radiation therapy and chemotherapy.
Angiogenesis Inhibitors in the Treatment of Cancer
Angiogenesis plays an important role in the growth and spread
of cancer. New blood vessels "feed" the cancer cells
with oxygen and nutrients allowing these cells to grow, invade
nearby tissue, spread to other parts of the body, and form new
colonies of cancer cells.
Scientists are trying to find ways to stop angiogenesis. They
are studying natural and synthetic angiogenesis inhibitors (also
called anti-angiogenesis agents) in the hope that these chemicals
will prevent the growth of cancer by blocking the formation of
new blood vessels. In animal studies, angiogenesis inhibitors
have successfully stopped the formation of new blood vessels causing
the cancer to shrink and die. Whether angiogenesis inhibitors
will be effective against cancer in humans is not yet known. The
process of producing and testing is likely to take several years.
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