Hodgkin's disease is one of a
group of cancers called lymphomas. Lymphoma is a general term
for cancers that develop in the lymphatic system. Hodgkin's
disease, an uncommon lymphoma, accounts for less than 1 percent
of all cases of cancer in this country. Other cancers of the
lymphatic system are called non-Hodgkin's lymphomas.
Non-Hodgkin's lymphomas are the subject of another NCI booklet,
What You Need To Know About™ Non-Hodgkin's Lymphoma.
The lymphatic system is part of the body's immune system. It
helps the body fight disease and infection. The lymphatic system
includes a network of thin lymphatic vessels that branch, like
blood vessels, into tissues throughout the body. Lymphatic
vessels carry lymph, a colorless, watery fluid that contains
infection-fighting cells called lymphocytes. Along this network
of vessels are small organs called lymph nodes. Clusters of
lymph nodes are found in the underarms, groin, neck, chest, and
abdomen. Other parts of the lymphatic system are the spleen,
thymus, tonsils, and bone marrow. Lymphatic tissue is also found
in other parts of the body, including the stomach, intestines,
and skin.
Cancer is a group of many related diseases that begin in cells,
the body's basic unit of life. To understand Hodgkin's disease,
it is helpful to know about normal cells and what happens when
they become cancerous. The body is made up of many types of
cells. Normally, cells grow and divide to produce more cells
only when the body needs them. This orderly process helps keep
the body healthy. Sometimes cells keep dividing when new cells
are not needed, creating a mass of extra tissue. This mass is
called a growth or tumor. Tumors can be either benign (not
cancerous) or malignant (cancerous).
In Hodgkin's disease, cells in the lymphatic system become
abnormal. They divide too rapidly and grow without any order or
control. Because lymphatic tissue is present in many parts of
the body, Hodgkin's disease can start almost anywhere. Hodgkin's
disease may occur in a single lymph node, a group of lymph
nodes, or, sometimes, in other parts of the lymphatic system
such as the bone marrow and spleen. This type of cancer tends to
spread in a fairly orderly way from one group of lymph nodes to
the next group. For example, Hodgkin's disease that arises in
the lymph nodes in the neck spreads first to the nodes above the
collarbones, and then to the lymph nodes under the arms and
within the chest. Eventually, it can spread to almost any other
part of the body. |