Leukemia is cancer of the white blood cells. This
cancer starts in the bone marrow but can then
spread to the blood, lymph nodes, the spleen,
liver, central nervous system and other organs.
In contrast,
other types of cancer can start in these organs
and then spread to the bone marrow (or elsewhere).
Those cancers are not leukemia. Both children
and adults can develop leukemia.
Leukemia is a complex disease with many different
types and sub-types. The kind of treatment given
and the outlook for the person with leukemia vary
greatly according to the exact type and other individual
factors.
There are four major types of leukemia:
acute vs. chronic
lymphocytic vs. myelogenous
- Acute means rapidly
growing. Although the cells grow rapidly, they
are not able to mature properly.
- Chronic refers to
a condition where the cells look mature but they
are not completely normal. The cells live too
long
and cause a build-up of certain kinds of white
blood cells.
- Lymphocytic and myelogenous (or
myeloid) refer to the two different cell types
from which leukemias start. Lymphocytic
leukemias develop from lymphocytes in the
bone marrow. Myelogenous leukemia (sometimes referred
to as myelocytic) develops from either of two
types of white blood cells: granulocytes
or monocytes.
By looking at whether a
leukemia is acute or chronic and myelogenous or
lymphocytic, most cases of leukemia can be sorted
into one of
four main types. And while both children and adults
can develop leukemia, certain types are more common
in one age group than in another.
Source: American Cancer Society
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