Leukemia
Leukemia is a type of cancer. Cancer is a group of many
related diseases. All cancers begin in cells, which make up blood and other tissues.
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.
The term leukemia refers to cancers of the white blood cells, which are also referred to as leukocytes or WBCs.
When a child has leukemia, large numbers of abnormal white blood cells
are produced in the bone marrow. These abnormal white cells crowd the
bone marrow and flood the bloodstream, but they cannot perform their
proper role of protecting the body against disease because they are
defective.
As leukemia progresses, the cancer interferes with the body's
production of other types of blood cells, including red blood cells and
platelets. This results in anemia
(low numbers of red cells) and bleeding problems, in addition to the
increased risk of infection caused by white cell abnormalities.
As a group, leukemias account for about 25% of all childhood cancers
and affect about 2,200 American young people each year. Luckily, the
chances for a cure are very good with leukemia. With treatment, most
children with leukemia are free of the disease without it coming back. 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. Leukemia is cancer
that begins in blood cells.
Normal Blood Cells
Blood cells form in the bone marrow. Bone
marrow is the soft material in the
center of most bones.
Immature blood cells are called stem cells and blasts.
Most blood cells mature in the bone marrow and then move into the blood vessels.
Blood flowing through the blood vessels and heart is called the peripheral
blood.
The bone marrow makes different types of blood cells. Each type has a special
function:
White
blood cells help fight infection.
Red
blood cells carry oxygen to tissues throughout the body.
Platelets help form
blood clots that control bleeding.
Leukemia Cells
In people with leukemia, the bone
marrow produces abnormal white blood
cells. The abnormal cells are leukemia cells. At first, leukemia cells
function almost normally. In time, they may crowd out normal white blood
cells, red blood cells, and platelets. This makes it hard for blood to
do its work.
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