Definition of Acute myeloid leukemia
Acute myeloid leukemia definition - medical term A quickly progressive malignant disease in which
there are too many immature blood-forming cells in the blood and bone marrow, the
cells being specifically those destined to give rise to the granulocytes or monocytes,
both types of white blood cells that fight infections. In AML, these blasts do not
mature and so become too numerous. AML can occur in adults or children. Acute myeloid
leukemia is abbreviated AML (pronounced A M L). It is also known as acute myelogenous
leukemia or acute nonlymphocytic leukemia (ANLL).
The early signs of AML may be similar to the flu or other common diseases with
fever, weakness and fatigue, loss of weight and appetite, and aches and pains in
the bones or joints. Other signs of AML may include tiny red spots in the skin,
easy bruising and bleeding, frequent minor infections, and poor healing of minor
cuts.
First, blood tests are done to count the number of each of the different kinds
of blood cells and see whether they are within normal ranges. In AML, the red blood
cell levels may be low, causing anemia; platelet levels may be low, causing bleeding
and bruising; and the white blood cell levels may be low, leading to infections.
A bone marrow biopsy or a bone marrow aspiration may be done if the results of
the blood tests are abnormal. During a bone marrow biopsy, a hollow needle is inserted
into the hip bone to remove a small amount of the marrow and bone for examination
under a microscope. In a bone marrow aspirate, a small sample of liquid bone marrow
is withdrawn through a syringe.
A lumbar puncture, or spinal tap, may be done to see if the disease has spread
into the cerebrospinal fluid, which surrounds the central nervous system (CNS) --
the brain and spinal cord.
Other key diagnostic tests may include flow cytometry (in which cells are passed
through a laser beam for analysis), immunohistochemistry (using antibodies to distinguish
between types of cancer cells), cytogenetics (to determine chromosome changes in
cells), and molecular genetic studies (DNA and RNA tests of the cancer cells).
The primary treatment of AML is chemotherapy. Radiation therapy is less common;
it may be used in certain cases. Bone marrow transplantation is under study in clinical
trials and is coming into increasing use.
There are two phases of treatment for AML. The first phase is called induction
therapy. The purpose of induction therapy is to kill as many of the leukemia cells
as possible and induce a remission, a state in which there is no visible evidence
of disease and blood counts are normal. Patients may receive a combination of drugs
during this phase including daunorubicin, idarubicin, or mitoxantrone plus cytarabine
and thioguanine. Once in remission with no signs of leukemia, patients enter a second
phase of treatment.
The second phase of treatment is called post-remission therapy (or continuation
therapy). It is designed to kill any remaining leukemic cells. In post-remission
therapy, patients may receive high doses of chemotherapy, designed to eliminate
any remaining leukemic cells. Treatment may include a combination of cytarabine,
daunorubicin, idarubicin, etoposide, cyclophosphamide, mitoxantrone, or cytarabine.
There are a number of different subtypes of AML. AML is classified using a system
called the French American British (FAB) system. In the this system, the subtypes
of AML are grouped according to the particular cell line in which the disease developed.
There are eight distinct types of AML, designated M0 through M7. Types M2 (myeloblastic
leukemia with maturation) and M4 (myelomonocytic leukemia) each account for 25%
of AML; M1 (myeloblastic leukemia, with few or no mature cells) accounts for 15%;
M3 (promyelocytic leukemia) and M5 (monocytic leukemia) each account for 10% of
cases; the other subtypes are rarely seen. AML is also classified according to the
chromosomal abnormalities in the malignant cells.
The treatment of the subtype of AML called acute promyelocytic leukemia (APL)
differs from that for other forms of AML. (APL is M3 in the FAB system.) Most APL
patients are now treated first with all-trans-retinoic acid (ATRA) which induces
a complete response in 70% of cases and extends survival. APL patients are then
given a course of consolidation therapy, which is likely to include cytosine arabinoside
(Ara-C) and idarubicin.
Bone marrow transplantation is used to replace the bone marrow with healthy bone
marrow. First, all of the bone marrow in the body is destroyed with high doses of
chemotherapy with or without radiation therapy. Healthy marrow is then taken from
another person (a donor) whose tissue is the same as or almost the same as the patient's.
The donor may be a twin (the best match), a brother or sister, or a person who is
otherwise related or not related. The healthy marrow from the donor is given to
the patient through a needle in the vein, and the marrow replaces the marrow that
was destroyed. A bone marrow transplant using marrow from a relative or from a person
who is not related is called an allogeneic bone marrow transplant. A greater chance
for recovery occurs if the doctor chooses a hospital that does more than five bone
marrow transplantations per year.
The overall chance of recovery (the long-term prognosis) depends on the subtype
of AML and the patient's age and general health.
Common Misspellings: acute myeloid leukaemia, acute myeloid lukemeya, acute myeloid
lukemia, acute myeloid luekemia, acute myeloid leukimia
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