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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:
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Benign tumors are not cancer:
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Benign tumors are rarely life-threatening.
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Most 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.
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Malignant tumors are cancer:
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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 tumor and entering
the bloodstream or the
lymphatic system.
The cells invade other organs and form
new tumors that damage these organs. The spread of cancer is called
metastasis.
Stomach cancer can affect nearby organs and
lymph nodes:
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A stomach tumor can grow through the stomach's outer layer into nearby organs,
such as the
pancreas,
esophagus, or intestine.
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Stomach cancer cells can spread through the blood to the
liver,
lungs,
and
other organs.
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Cancer cells also can spread through the lymphatic system to lymph nodes all
over the body.
When cancer spreads from its original place to another part of the body, the
new tumor has the same kind of abnormal cells and the same name as the original
tumor. For example, if stomach cancer spreads to the liver, the cancer cells in
the liver are actually stomach cancer cells. The disease is metastatic stomach
cancer, not liver cancer. For that reason, it is treated as stomach cancer, not
liver cancer. Doctors call the new tumor "distant" or metastatic disease.
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