Cancer
Types of Childhood Cancers
There are
many types of childhood cancers and it can affect any part of the body. Some of the
diseases occur commonly enough that the doctors, nurses, and other care providers develop
a ready familiarity and an almost standard approach. Others are so rare that an individual
hospital may see less than one case per year. Therefore, the type of information that is
available varies widely. Despite this many general principles apply even to the rarest of
cancers. This general information can give you a framework on which to search for more
specific answers to your questions.
What
is it?
Cancer is
basically a group of diseases. What these groups of diseases have in common is that they
involve the uncontrolled growth of certain cells in the body. Normally, in our bodies,
cells grow and divide to replace cells as they die on a daily basis. Normal cells have an
internal control that tells them to grow at a rate that does not exceed the cells that
die. The growth is regulated and orderly. In cancer, cells become "transformed"
and grow in an unregulated matter and show no respect for boundaries. The overproduction
of cancer cells can push normal cells out of the way (invade) and can spread through the
blood and grow in other sites away from the original cancer cells (metastasize). These two
features define a cancerous growth. The type of cancer that develops depends on which cell
type was transformed.
In general,
it takes many years for a cancer to develop. That is why 98% of cases of cancer are in
adults, especially older adults. About one out of every six adults will develop cancer in
their lifetime while only one in every 330 persons will develop cancer before age 20.
Children’s cancers occur in the developing tissues, called embryonal tissues.
Examples of this are the developing blood system, developing brain, and the developing
kidney. Adults get cancers of organs that are already formed such as lungs, colon, and
breast. Teenagers get cancers that are more similar to what is seen in children rather
than adults.
What
causes it?
We do
not know what causes childhood cancers, but we do know that lifestyle factors and
environment play little role. We do know that there are risk factors that are both genetic
and environmental. Research has particularly focused on how environmental factors in the
presence of specific genetic changes promote cancer. An example of a genetic change that
is associated with having an increased risk of childhood cancer is Down’s syndrome.
Children with Down’s syndrome have an extra chromosome and have a 20 fold increased
risk of developing leukemia.
What
are the symptoms?
Because childhood cancers arise from the developing tissues rather than organs, they are
often deep-seated and do not present with the obvious visual, palpable, or functional
abnormalities until they are quite large. Childhood cancers also grow relatively quickly.
That is why about 80% of children with cancer will have metastases at diagnosis. This
biological behavior also makes these cancers very responsive to chemotherapy and much more
readily treatable and curable than the cancers seen in adult.
Diagnosis
and treatment?
The majority of children who are diagnosed with childhood
cancer do not have a history of any specific risk factors and the cause of their cancer
cannot be pinpointed. An active area of research is to better understand the causes and
nature of childhood cancer. This will not only mean better treatment strategies but
hopefully we will one day understand how to prevent childhood cancer and make it a truly
rare event.
The treatment
of childhood cancer has enjoyed remarkable progress, even without a solid understanding of
what causes it. For cancers in adults there is a strong relationship to environmental
exposures and life-styles factors and up to 80% of adult cancers may be preventable.
This information has been designed as a comprehensive and quick reference
guide written by our health care reviewers. The health information written
by our authors is intended to be a supplement to the care provided by your
physician. It is not intended nor implied to be a substitute for
professional medical advice.
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