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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:
-
Benign tumors are rarely life-threatening.
-
Generally, benign tumors can be removed, and they usually do not grow back.
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Cells from benign tumors do not invade the tissues around them.
-
Cells from benign tumors do not spread to other parts of the body.
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Malignant tumors are cancer:
-
Malignant tumors are generally more serious than benign tumors. They may be
life-threatening.
-
Malignant tumors often can be removed, but sometimes they grow back.
-
Cells from malignant tumors can invade and damage nearby tissues and organs.
-
Cells from malignant tumors can spread to other parts of the body. The cells
spread by breaking away from the original cancer
(primary tumor)
and entering
the bloodstream or
lymphatic system.
They invade other organs, forming new
tumors and damaging these organs. The spread of cancer is called
metastasis.
Oral cancer is part of a group of cancers called
head and neck cancers. Oral
cancer can develop in any part of the oral cavity or oropharynx. Most oral
cancers begin in the tongue and in the floor of the mouth. Almost all oral
cancers begin in the flat cells
(squamous cells)
that cover the surfaces of the
mouth, tongue, and lips. These cancers are called
squamous cell carcinomas.
When oral cancer spreads (metastasizes), it usually travels through the
lymphatic system. Cancer cells that enter the lymphatic system are carried
along by
lymph,
a clear, watery fluid. The cancer cells often appear first in
nearby
lymph nodes
in the neck.
Cancer cells can also spread to other parts of the neck, the lungs, and other
parts of the body. When this happens, the new tumor has the same kind of
abnormal cells as the primary tumor. For example, if oral cancer spreads to the
lungs, the cancer cells in the lungs are actually oral cancer cells. The
disease is metastatic oral cancer, not lung cancer. It is treated as oral
cancer, not lung cancer. Doctors sometimes call the new tumor "distant" or
metastatic disease.
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