A cancer is a group of abnormal cells, known as a tumor, that grows
uncontrollably. Cancerous tumors invade and destroy surrounding tissue. Not all tumors
are cancerous. Benign tumors, which are not cancerous, do not invade and destroy
tissue. However, a benign tumor may grow very large. Cancerous tumors may shed
cancer cells that spread to other parts of the body. This is called a
Benign tumors do not spread in this way.
What is going on in the body?
A chromosome is genetic material within the nucleus of a cell. Chromosomes
provide the so-called blueprints that direct normal cell function. The nucleus that houses
the chromosomes is the control center for the cell. The nucleus of a normal cell, such
as a muscle cell, controls its activity as part of a larger tissue, a muscle. The cell will
then act in concert with other cells of that muscle to expand and contract, causing
motion. Damage to the nucleus prevents the cell from behaving normally.
Cancer occurs when the damage causes changes that make the cell grow
and divide wildly. When a cell becomes cancerous, over time a tumor forms from these abnormal
cells. Because the tumor is made up of defective cells, it cannot function as it
should. The body suffers in two ways:
from both the loss of the normal function of that tissue, and
from the damage to other tissues
A cancer is named by the type of organ tissue from which it developed. For
example, breast cancer will always be called breast cancer, even if it spreads to other
body parts. The type of tissue within an organ that underwent the cancerous change
also further identifies a cancer. For example, lung cancer is grouped into several groups
depending on exactly what kind of lung tissue was affected. A cancerous tumor does
not grow any faster than the kind of tissue from which it started. But it does keep growing
and multiplying uncontrollably. Healthy tissue does not grow constantly.
In the early stages of any cancer, you may not be able to see much of an
effect on the body. But cancer cells can break off from the main tumor and travel through
your blood stream to other parts of your body. These cancer cells may then form new
tumors, known as metastases. As the cancer grows and spreads, or metastasizes,
the person will likely begin to weaken. Cancer makes it hard for your body to function normally.
In the advanced stages of cancer, symptoms such as weight loss,
weakness, and fatigue are common. At the same time, new cancerous tumors that
spread to other parts of the body may cause other organs to fail. If not successfully
treated, the cancer will destroy the functioning of vital body systems. This can lead to
These vital body functions include:
breathing when the lungs are involved
regulation of body functions when the brain is involved
waste removal when the liver or kidneys are involved
Most cancers occur in people older than age 55. This may be
because cells become more vulnerable to damage after years of use. It is possible for
children to have cancer, but this is rare. More men than women have cancer. The
most common cause of cancer death in men and women is lung cancer.
What are the causes and risks of the disease?
For cancer to occur, something must damage the nucleus of the cell. Some
people are born with a tendency for cancer. Their cells may be more vulnerable to
the kind of damage that leads to cancer. For others, the damage occurs after years of
exposure to substances that can cause cancer. Tobacco from any source is very
dangerous. Certain chemicals, unprotected sun exposure, and radiation can all cause