There are two classification criteria for leukemia which determines the
type of leukemia. It involves the 1). rate or duration of developement,
and the 2). type of bone marrow cells that are affected. These classification
1. Developmental and progression rate
According to this criteria, leukemia is classified as chronic or acute:
CHRONIC LEUKEMIA: This is a type of leukemia
characterized by a slow progression. In its early stages, chronic
leukemia is asymptomatic, because the small number of abnormal white
blood cells still can carry out some of the normal white blood cells
functions. Symptoms occur in advanced stages when the number of abnormal
white blood cells increases.
ACUTE LEUKEMIA: This is a type of leukemia characterized
by a rapid onset and course caused by an increased number of abnormal
white blood cells. Acute leukemia can be fatal within weeks or months
if not treated.
2. Type of bone marrow
cells affected, which include:
Lymphocytic (also called lymphoblastic):
This is a type of leukemia that affects the lymphocyte cells
in bone marrow. Lymphocytes are a a type of leukocyte (white
blood cell), that are suppose to increase in number when it's
necessary to fight infection. There are 3 types of lymphocyte
cells which include: natural killer cells (large), and T-cell
(small), and B-cells (small).
Myelogenous (also called myeloid):
This is a type of leukemia that affects the myeloid cells
in bone marrow. Myeloid cells go on to form red cells, white
blood cells that are NOT lymphocytic, and platelets.
According to the above Chronic/Acute -AND- Lympocyte/Myeloid
criteria, there are 4 main types of leukemia:
Each of these 4 main types is then further broken down into subtypes,
including a rare type of chronic leukemia called Hairy Cell Leukemia
which is classified as a sub-type of Chronic Lymphocytic Leukemia.
Most cancers are staged on the I, II, III, and IV system which reflects
the rate of tumor development and/or progression. However, the staging
for leukemia is a little bit different.
"Because leukemia already involves all of the bone marrow
in the body, and in many cases, has spread to other organs such as the
liver, spleen, and lymph nodes, the staging of leukemia depends on other
information that reflects the patient's outlook for survival. Different
staging systems are used for different types of chronic leukemia. Some
types do not have any staging system." - American Cancer Society.
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