DISEASES
Acute Leukemia
INTRODUCTION
Acute
leukemia consists of a group of diseases characterized by
the presence of a great number of immature cells that proliferate
in the blood stream and the bone marrow. They affect the
patient
in different ways but usually, symptoms appear as anemia
(paleness and exhaustion), bleeding or repeated infections that
are difficult to cure. Leukemia is diagnosed performing a “bone
marrow vacuum study” consisting of the extraction
of a small amount of cells located inside the center
of the bones; it is usually extracted from the iliac crest,
breastbone and in very small children, from the shin bone.
The cells are then stained and examined under the microscope.
Diagnosis and treatment must be performed by an hematologist.
Acute leukemia can be divided in two main groups: 1) Lymphoblastic
Acute Leukemia (LAL) and 2) Non Lymphoblastic Acute Leukemia
(also called Myeloblastic Leukemia or AML). A third group
corresponds to those leukemias that are neither AML or ALL.
Several subgroups exist within the former two main groups, usually
classified
with a letter and a number. This classification refers to
the form and origin of leukemia cells and it does not necessarily
have a pronognostic value.
One
of the most common ways to classify acute leukemia is the following:
Acute lymphoblastic leukemia: L1, L2, and L3. Non lymphoblastic
acute leukemia: M0, M1, M2, M3, M4, M5, M6 and M7.
CONVENTIONAL TREATMENT
Conventional
treatment of acute leukemia includes the use of different
drugs known as “Chemotherapy”. This treatment is applied
to the patient on a cyclic basis. The cycle includes one or more
drugs given periodically to the patient. The first treatment cycle
for all leukemia’s is the strongest and requires a longer
stay in the hospital as an in-patient. The intention of this cycle
is to achieve complete remission, which means to clean the patient
of malignant cells, trying to get under 5% leukemia cells in the
bone marrow. It is very important to achieve as well, normal clinical
and laboratory data. Total remission does not indicate “cure” and
suspending treatment may lead to re-appear of leukemia (relapse)
. Thus, treatment must continue in every patient. The type
and duration of treatment, depends on a variety of factors such
as the leukemia type, chromosomic alterations, patients
gender, age, and the particular ways for the disease to
behave, among others.
There
are many ways to measure treatment effectiveness, and some of
them are:
Toxicity
level is measured by nausea, hair lost, immunologic weakness,
etc
Morbility
and mortality is assessed by the number of patients who continue
with the disease and die due to the treatment.
Complete
remission is evaluated by patients who achieve total remission,
which means the amount of patients who achieve an apparent
state of health regardless of relapse.
Global
survival means the amount of patients who are alive 3-5 years
after diagnosis.
Disease
free survival is the average of patients who are alive, with or
without the disease, 3-5 years after they have been diagnosed.
From
this different assessment methods, the last is the most
valuable to patients and family members of the patient,
and is also the
parameter frequently used by the hematologist to decide
which treatment he should apply.
If
complete remission is not achieved, other therapies must
be used. This is the case of “high risk patients”,
those that either do not respond to the conventional treatment
or carry chromosomic
alterations that will not disappear with this therapeutic
approach. Bone marrow transplantation is the only tool to
give an opportunity
of life to this kind of patients. Moreover, the likelihood
of survival is ZERO, five years after chemotherapy, if an
high risk
patient does not receive a bone marrow transplant.
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