NEUROBLASTOMA FACTS
Neuroblastoma is a form of cancer that occurs in infants and
young children.
It is rarely found in children older than 10 years.
The cells of this cancer
usually resemble very primitive developing
nerve cells found in an embryo
or fetus. (The term
neuro
indicates "nerves," while
blastoma refers to a
cancer that
affects immature or developing cells).
Neurons (nerve cells) are the main component of the brain and
spinal cord
and of the nerves that connect them to the rest of the
body. These cells
are essential for thinking, sensation, and
movement. There is a part of the nervous system that we are rarely
aware of, called the
autonomic nervous system, which controls
involuntary body functions such as heart rate, blood pressure, and
digestion. The
sympathetic nervous system is a part of the
autonomic nervous system.
It includes:
- nerve fibers that run alongside the spinal cord
- clusters of nerve cells called ganglia (plural of
ganglion) at certain
points along the path of the nerve fibers
- nerve-like cells found in the medulla (center) of the
adrenal glands.
The adrenals are triangular-shaped glands located
above the kidneys.
The hormone adrenaline comes from the cells in
the adrenal gland.
Most neuroblastomas (about two thirds) start in the abdomen.
About one
third of neuroblastomas start in the adrenal glands and
another third begin
in the sympathetic nervous system ganglia of the
abdomen. The rest start
in sympathetic ganglia of the chest or neck
or in the pelvis. Some can start
in the spinal cord. Rarely, a
neuroblastoma may have spread so extensively
by the time it is found
that doctors are unable to determine exactly where
it started.
Not all childhood autonomic nervous system tumors are malignant
(cancerous). There is a benign tumor called
ganglioneuroma
which is
composed of mature ganglion and nerve sheaths that do not
continue to
grow.
Ganglioneuroblastoma is a tumor that has both malignant
and benign parts.
It contains
neuroblasts (immature nerve
cells) that can grow and spread abnormally, as well as areas of
benign tissue that are similar to
ganglioneuroma.
Ganglioneuromas are usually removed by surgery and
carefully
examined under a microscope to be certain they do not have areas
of
ganglioneuroblastoma. If the final diagnosis is ganglioneuroma, no
additional treatment is needed. In contrast, ganglioneuroblastomas
are treated the
same as neuroblastomas.
Neuroblastoma is a unique cancer in many ways. It is one of the
few
cancers in children that release hormones that can cause strange
changes
in the body, such as constant diarrhea. It can also cause
changes in the
some functions of the brain, such as
opsoclonus (rotary movements of the
eyes) and
myoclonus (spastic jerks of the muscles).
These changes are called
paraneoplastic syndromes.
The tumor itself can behave strangely. Sometimes the cells die
without any cause and the tumor disappears. This is part of a normal
process known as programmed cell death
(apoptosis), the
normal process that occurs when
cells die. This tumor disappearance
is much more common in very young
infants than in older children.
Another behavior that is unusual for childhood tumors is that the
cells sometimes mature spontaneously to normal ganglion cells and
stop dividing.
This causes the tumor to become a ganglioneuroma,
which is benign (non-cancerous).
