Leukemia is cancer of the white blood cells. It develops in
the bone marrow and spreads into the blood and to other
organs. There are several types of leukemia. They are
grouped in two ways: by how rapidly the disease develops
(acute vs. chronic leukemia) and by the type of blood cell
involved (lymphocytic and myeloid leukemia being the most
common). In acute leukemia, bone marrow cells are
immature and are unable to function normally. The number
of abnormal cells increases rapidly. In chronic leukemia,
cells are more mature and can carry out some of their
normal functions. The number of abnormal cells increases
more slowly. The most common types of leukemia are acute
lymphocytic leukemia, acute myeloid leukemia, chronic
lymphocytic leukemia, and chronic myeloid leukemia. In
children leukemia is the most common cancer, and acute
lymphocytic leukemia is the most common type of leukemia.
In adults, acute myeloid leukemia is the most common
occurring type, followed by chronic lymphocytic leukemia