Cancer is ultimately the result of cells that uncontrollably grow and do
not die. Normal cells in the body follow an orderly path of growth,
division, and death. Programmed cell death is
called apoptosis, and when this process breaks down, cancer begins to
form. Unlike regular cells, cancer cells do not experience programmatic
death and instead continue to grow and
divide. This leads to a mass of abnormal cells that grows out of
control.
What is cancer? - Video
A short, 3D, animated introduction to cancer. This was originally
created by BioDigital Systems and used in the Stand Up 2 Cancer
telethon.
Genes - the DNA type
Cells can experience uncontrolled growth if there are damages or
mutations to DNA, and therefore, damage to the genes involved in cell
division. Four key types of gene are responsible
for the cell division process: oncogenes tell cells when to divide,
tumor suppressor genes tell cells when not to divide, suicide genes
control apoptosis and tell the cell to kill itself if
something goes wrong, and DNA-repair genes instruct a cell to repair
damaged DNA.
Cancer occurs when a cell's gene mutations make the cell unable to
correct DNA damage and unable to commit suicide. Similarly, cancer is a
result of mutations that inhibit oncogene and
tumor suppressor gene function, leading to uncontrollable cell growth.
Carcinogens
Carcinogens are a class of substances that are directly responsible for
damaging DNA, promoting or aiding cancer. Tobacco, asbestos, arsenic,
radiation such as gamma and x-rays, the
sun, and compounds in car exhaust fumes are all examples of carcinogens.
When our bodies are exposed to carcinogens, free radicals are formed
that try to steal electrons from other
molecules in the body. Theses free radicals damage cells and affect
their ability to function normally.
Genes - the family type
Cancer can be the result of a genetic predisposition that is inherited
from family members. It is possible to be born with certain genetic
mutations or a fault in a gene that makes one
statistically more likely to develop cancer later in life.
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