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A risk factor is anything that changes your chance of getting
a disease such as cancer. Different cancers have different risk
factors. Lifestyle-related risks are thought to be the main factors
that affect cancer risk in adults. Examples include the effect of
unhealthy diets, not enough exercise, and habits like smoking and
drinking alcohol. Lifestyle-related risk factors have little or no
affect on childhood cancer.
Cancer is caused by a mutation (change) in a gene. Over the
past few years, scientists have made great progress in understanding
how certain changes in a person's DNA can cause cells of the body to
become cancer. DNA carries the instructions for nearly everything our
cells do. We usually look like our parents because they are the source
of our DNA. But DNA affects more than how we look. It also affects our
risks for developing certain diseases, including some kinds of cancer.
When children are born with mutated DNA that was inherited from
parents, the mutations are present in every cell of the child's body.
This means the mutations can be found by testing the DNA of blood cells
or other body cells.
Most cancers, though, are not caused by inherited DNA
mutations. They are the result of DNA changes that happened early in
the child's lifetime. Every time a cell prepares to divide into 2 new
cells, it must copy its DNA. This process is not perfect, and errors
sometimes occur. Luckily, cells have repair systems that "proofread"
DNA. Some errors can still slip past, especially when the cells are
growing quickly. This kind of gene mutation can happen at any time in
life and is called an acquired
mutation.
Acquired mutations start in one cell of the body, and that
cell passes the mutation on to all the cells that come from it. These
acquired mutations are present only in the person's cancer cells and
will not be passed on to his or her children. Although the causes of
mutations responsible for certain adult cancers are known (for example,
cancer-causing chemicals in cigarette smoke), the reasons for DNA
changes that cause childhood cancers are not known. Some of these
changes can take place in developing fetuses and are already present at
birth.
Last Medical Review: 05/19/2009
Last Revised: 05/19/2009
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