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.