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Understanding Cancer
Cancer begins in cells, the building blocks that make up
tissues.
Tissues make
up the organs of the body.
Normally, cells grow and divide to form new cells as the body needs them. When
cells grow old, they die, and new cells take their place.
Sometimes, this orderly process goes wrong. New cells form when the body does
not need them, and old cells do not die when they should. These extra cells can
form a mass of tissue called a growth or
tumor.
Tumors can be
benign
or
malignant:
Benign tumors are not cancer:
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Benign tumors are rarely life-threatening.
-
Generally, benign tumors can be removed. They usually do not grow back.
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Cells from benign tumors do not invade the tissues around them.
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Cells from benign tumors do not spread to other parts of the body.
Malignant tumors are cancer:
-
Malignant tumors are generally more serious than benign tumors. They may be
life-threatening.
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Malignant tumors often can be removed. But sometimes they grow back.
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Cells from malignant tumors can invade and damage nearby tissues and organs.
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Cells from malignant tumors can spread (metastasize)
to other parts of the
body. Cancer cells spread by breaking away from the original
(primary)
tumor
and entering the bloodstream or
lymphatic system. The cells invade other organs
and form new tumors that damage these organs. The spread of cancer is called
metastasis.
When breast cancer cells spread, the cancer cells are often found in lymph
nodes near the breast. Also, breast cancer can spread to almost any other part
of the body. The most common are the bones, liver, lungs, and brain. The new
tumor has the same kind of abnormal cells and the same name as the primary
tumor. For example, if breast cancer spreads to the bones, the cancer cells in
the bones are actually breast cancer cells. The disease is metastatic breast
cancer, not bone cancer. For that reason, it is treated as breast cancer, not
bone cancer. Doctors call the new tumor "distant" or metastatic disease.
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