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 Introduction
 Leukemia means "white blood" but it is not as commonly called,
blood cancer. It is a cancer of the tissues in which blood is formed.
Bone marrow, the soft, spongy center of
the bone, produces red blood cells, white blood cells and platelets.
Red blood cells carry oxygen to cells
through- out the body and, if there are too few, symptoms such as
anemia, shortness of breath appear: white blood cells fight infection,
and platelets, which control blood clotting, prevent hemorrhaging.
The spleen and the lymph nodes produce
a type of white blood cell called lymphocyte. Lymphocytes produce
antibodies, act against infection, and contribute to the body's own
immune system.
All blood-forming tissues daily release
millions of each type of cell into one of the body's two circulatory
systems-the blood vessel system and the lymph system. When leukemia
strikes, millions of abnormal, immature white blood cells called
leukocytes are released into these circulatory systems.
Because these cells are immature, they
cannot carry out their basic function of fighting infection. In advanced
leukemia, the uncontrolled multiplication of abnormal cells results in
crowding out the production of normal white cells to fight infections,
of platelets to control hemorrhaging and of red blood cells to prevent
anemia.
There are several types of leukemia,
depending on the white cell that is multiplying. About 90 percent of
cases are caused by two types of leukocytes: lymphocytic leukemia (also
called lymphoblastic), involving cells formed in lymphatic tissue and
granulocytic leukemia (also called myelocytic), involving cells found in
bone-marrow.
Both the lymphatic and granulocytic
types have acute or swift growing, and chronic or slow growing, forms.
The two types of cells and two rates of growth produce four main types
of leukemia in human beings: acute lymphocytic, chronic lymphocytic,
acute granulocytic and chronic granulocytic.
Risk Factors
The causes of most cases of human leukemia are unknown. Excessive
exposure to radiation and to certain chemicals, such as benzene, have
been linked to the development of leukemia. Certain viruses are known to
cause leukemia in animals, but this has not been proven so in humans.
There is some evidence of an inherited susceptibility but none that the
disease is transmitted directly from parent to child, It is known that
there is a higher than normal incidence of leukemia among children with
Down's syndrome (mongolisR1), and certain other hereditary abnormalities
may be linked to leukemia.
Age is a factor to the extent that the
different types of leukemia generally strike different age groups.
Leukemia strikes more children than any
other form of cancer and is the leading cause of death by disease among
chlldren aged 3 to 15. The type of leukemia common among children is
acute lymphocytic leukemia. Fortunately it is with this type of
childhood leukemia that the greatest progress in treatment and survival
is being made. Children do get acute granulocytic leukemia, but much
less frequently.
The type of leukemia most prevalent in
young adults is acute granulocytic.
Chronic leukemia, whether granulocytic
or lymphocytic, generally appears after the age of 40. Adult may also be
struck by acute leukemia, however-either granulocytic or lymphocytic.
More than half of all cases of leukemia
occur in persons over 60 years of age.
Signs and
Symptoms
There are no definite early signs of leukemia.
Acute Leukemia
Acute leukemia in children usually appears rather suddenly with symptoms
similar to those of a cold and progresses rapidly. Lymph nodes, spleen
and liver become enlarged with white blood cells that accumulate in
these organs. Because leukemic cells circulate throughout the body via
the blood and lymph systems, the patient may develop a variety of
generalized complaints.
Early signs and symptoms may include
fatigue, paleness, loss of appetite, weight loss, repeated infections,
night sweats, bone and joint pain, fever, easy bruising, nose bleeds or
other hemorrhages. There may also be enlargement of the liver, spleen
and lymph nodes, and anemia.
Symptoms of advanced leukemia include
extreme fatigue, massive hemorrhages, pain, high fever, swelling of the
gums and various skin disorders.
Sometimes chronic leukemia in adults
later develop into acute leukemia. In these cases, the symptoms of the
acute from progress more slowly than in children.
Chronic Leukemia
Chronic leukemia comes on slowly and without warning signs. Many cases
are discovered during routine blood tests, but significant signs - and
symptoms may not appear for several years. When they do develop, signs
and symptoms resemble those of the acute forms of the disease; fatigue,
tendency to bruise and bleed easily, and increased susceptibility to
infections. The physician can often feel an enlarged spleen or lymph
nodes.
Diagnosis
Leukemia is diagnosed by microscopic examination of the blood and bone
marrow cells. Blood samples are taken in the usual way by drawing a
small amount of blood from a vein in the arm of finger. The bone marrow
sample biopsy) is taken by the aspiration technique, in which a needle
is inserted after skin anesthesia and the tissue sample withdrawn
through suction. The breastbone or the bone at the top of the hip is
usually selected for bone marrow biopsy. The patient will experience
only a slight sensation of pressure as the needle is inserted; when the
marrow is withdrawn, there will be a few seconds of pain which the
patient will be forewarned of by the physician.
These cell samples are examined for
excessive numbers of the abnormal white blood cells characteristic of
specific types of leukemia.
The blood samples reveal the number of
white blood cells, red blood cells and platelets in the blood and if
leukemic cells have entered the circulatory systems.
Treatment
Chemotherapy is by far the most effective current method of treating the
leukemias. It is combined with radiotherapy and surgery in specialized
conditions.
Chemotherapy
A variety of anti-cancer drugs, used singly and in combinations of two
or more drugs, achieve remissions in a high percentage of patients with
leukemia.
Remission is the complete or partial
disappearance of the signs and symptoms of a disease, or the period
during which a disease is under control.
The special drugs used in chemotherapy
produce more injury to cancer cells than to normal cells, but the
physician maintains a delicate balance between dose and frequency by
giving enough chemotherapy to kill leukemic cells without destroying too
many healthy ones. Chemotherapeutic drugs work in several different ways
but they usually interfere with cell division and growth. Rapidly
growing cells, both normal and cancer, are most vulnerable to
chemotherapeutic drugs.
There are certain side effects that may
occur. They include nausea and vomiting, diarrhea, hair loss, anemia,
reduced blood-clotting ability, susceptibility to infections, and mouth
sores.
Individuals tolerate drugs differently
and when treatment is stopped, side effects disappear; hair grows back,
for example, or anemia is corrected. Any unexpected side effects should
be reported to the physician.
Radiotherapy
Radiotherapy may be used in addition to the chemotherapeutic drugs for
treatment of leukemia patients. The basic principle of radiation therapy
is to bombard cancer cells with rays which damage or destroy the cancer
yet produce only minimum damage to surrounding normal tissues.
Radiotherapy is sometimes used to treat
acute leukemia following drug treatment. The purpose is to help kill
leukemic cells in the brain since that organ is not reached by most
anticancer drugs. Radiation may also be beamed to specific areas, such
as the lymph nodes, the spleen and the spine. Some patients are
benefited from total body irradiation.
Skin reactions, nausea, vomiting, a
feeling of tiredness can be side effects of radiation. Rest and good
nutrition help the body recover more quickly.
Surgery
Surgery has only limited usefulness in controlling leukemia. The spleen
may be removed in some cases for some types of leukemia, but only as one
part of the overall treatment. Biopsies, the surgical removal of
specimen tissues for microscopic examination, are performed only for
diagnostic purposes. Occasionally surgery may be performed for unusual
complications.
Supportive Therapy
As the disease progresses, the patient becomes increasingly subject to
infection, anemia and hemorrhage, due to interference with the
production of normal blood elements. The drugs used to treat leukemia,
unfortunately, also interfere with cell division and growth and, due to
their destructive power, may also produce other undesirable side
effects.
Supportive treatment are available to
help fight these conditions, and have been vital in maintaining patients
until the benefits of chemotherapy and/or radiation can take ·effect,
Transfusions of blood platelets are effective in preventing or stopping
hemorrhage. Antibiotics are used to prevent infection, as are strict
hygiene measures. Transfusions of granulocytes, infection-fighting white
blood cells, are also beneficial.
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Patient Education
