Therapy
for Leukemia
Treating
of Leukemia cancer includes following therapies:
Transfusion
of blood
The disease
processes of leukemia, myeloma, and many lymphomas interfere with the
normal production of red cells, white cells, and platelets in the
marrow. Thus, it is common for patients with these diseases to develop
anemia (low red cells) and thrombocytopenia (low platelets), and in
some cases, leukopenia (low white cells, either granulocytes or
lymphocytes or both). This can happen before treatment begins because
the cancer cells inhibit the production of normal blood cells in the
marrow. In addition, the drugs used to treat these diseases and which
stop the progression of or, in some cases, cure these diseases, often
injure healthy stem cells in the marrow as a side effect. These
precursor cells normally go on to produce red cells, white cells or
platelets. This injury to normal cells can cause temporary side effects
such as very low red cell or platelet counts for a period of a few
weeks, in most cases. During and after chemotherapy it is
possible to replace the red cells and platelets by cells donated by
healthy volunteers in the form of blood transfusions. Severe anemia (a
relative term, not well defined by scientific studies) or
thrombocytopenia can be life-threatening in extreme cases. Most doctors
specializing in the care of patients with blood cancers believe that
varying degrees of replacement by prophylactic red cell transfusion
represent a good practice to prevent complications of anemia, such as
fatigue, weakness, shortness of breath, or in extreme cases, heart
attack or stroke. Similarly, most physicians advocate giving
prophylactic platelet transfusions to reduce the likelihood of
bleeding. Unfortunately, practical methods of safely and
effectively transfusing adequate numbers of granulocytes or other white
cells are not yet available to prevent infection that occurs as a
result of low white cell count. White cell transfusion is usually
reserved for uncommon instances of severe infections with bacteria or
fungi that do not respond to antibiotics or anti-fungal drugs. Because
the yield of white cells from current collection techniques is
insufficient, some investigative studies and clinical protocols now
involve administering white cell growth factors (e.g., G-CSF) to
volunteer donors, particularly family members, prior to white cell
collection by hemapheresis. This increases the number of white cells
that are in the donor's circulation, thus improving the yield of white
cells collected. It is hoped that the larger number of white cells
collected in this manner will be more effective in fighting infection. The
need for transfusions varies depending on the type of blood disease in
question and the type of drugs used in the chemotherapy. For example,
almost all patients with leukemia (a disease primarily affecting the
marrow and blood) require some transfusions during their care. Many
patients with Hodgkin or non-Hodgkin lymphoma (diseases primarily
affecting the lymph nodes and spleen) may not require transfusions
unless they require a blood or marrow stem cell transplant or if the
lymphoma involves the marrow. Individual physicians take
different approaches in deciding if transfusion is appropriate for a
given patient because there is controversy as to how to best balance
the benefits and risks of transfusion in many clinical situations.
Studies comparing various indications for transfusions may help
physicians have a more scientific basis for their decisions, but
currently transfusion policies usually depend on the patient's
condition and an individual physician's training, experience and
long-held community standards of practice.
Transfusion of Red Cells
Red
cell transfusions are used to treat low red cell counts (anemia),
which, if untreated, can cause weakness, lethargy, and in extreme
cases, more severe symptoms such as shortness of breath or rapid
heartbeat. Most physicians prescribe red cell transfusions before a
patient develops serious symptoms, particularly when managing older
patients or those with a history of heart or blood vessel disease.
There are few scientific data that guide physicians as to the exact red
cell count at which to prescribe a transfusion. The age of the patient,
the level of his or her activity, the presence of other complicating
medical conditions, and the likelihood and timeliness of the recovery
of red cell production in the marrow each must be considered along with
the red cell count. All red cell transfusions need to be
matched to the patient in the laboratory, and for patients with blood
diseases the donated blood should always have the white cells removed
by filtration. "Leukoreduced" or "leukodepleted" are the medical terms
for white cell removal. Leukoreduction reduces the risks of fever and
chills after transfusion, reduces the risk of not responding to
platelet transfusions, and reduces the risk of transmission of some
viral infections (e.g., cytomegalovirus, HTLV-1). Some centers use
irradiation of all cell transfusions to patients receiving intensive
chemotherapy or who are considered to have impaired immune systems to
prevent a rare but potentially life-threatening complication of
transfusion called graft versus host disease. Patients undergoing blood
or marrow stem cell transplants generally should receive irradiated
blood components during the transplant period. Transfusion of Platelets
Platelet
transfusions are given to prevent or to treat bleeding due to severely
low platelet counts (thrombocytopenia). There is controversy as to
whether prophylactic platelet transfusions are necessary or beneficial,
although it seems that maintaining a platelet count of greater than
5,000, and sometimes higher, reduces the risk of minor bleeding (e.g.,
nose bleeds, bruises in the skin called ecchymoses, pinpoint bleeding
in the skin called petechiae). The platelet count at which most
hematologists and oncologists believe prophylactic transfusion (in the
absence of bleeding) is indicated has decreased from about 20,000 to
10,000 at most cancer centers, but there is great individual variation
from physician to physician within this range, and from patient to
patient. Uncommonly, patients bleed when their platelet counts go below
30,000, and most patients can tolerate stable platelet counts within a
range of 5,000 to 10,000 without bleeding. The need for surgery or
other invasive procedures often requires transfusion to maintain a much
higher platelet count during surgery and for a period of healing
thereafter. Platelets can be given as pools made from several
units of whole blood from different donors or single donor units
obtained by hemapheresis. There is disagreement among physicians as to
which approach is most appropriate; neither approach has been shown to
be definitively superior or inferior. Donated platelets should ideally
be ABO-identical with the patient's platelets, but there is controversy
as to how important this is. Donated platelet units should have
the white cells removed by filtration prior to transfusion and, if
appropriate, should be irradiated as well. In
patients with certain forms of cancer, the stem cells produce an excessive
number of defective or immature blood cells (as in leukemia). To eliminate the
cancer, very high doses of chemotherapy and sometimes radiation therapy are
given. These high-dose cancer-fighting treatments are needed to destroy the
abnormal stem cells and blood cells.
However, the treatments also damage normal cells found in bone marrow. After
the cancer treatments, healthy bone marrow (in the form of a transplant) is
given to restore normal stem cell function. The chemotherapy not only helps
destroy cancer cells but it also prepares the body to receive the transplanted
marrow so it will not be rejected.
Some patients may receive a bone marrow transplant to treat aplastic anemia
(in which the patient has low blood counts) and some immune deficiency diseases.
Chemotherapy is given to these patients to suppress the immune system, allowing
the transplanted marrow the best condition in which to grow. Without
chemotherapy, the patient's own immune system would likely destroy transplanted
marrow before it has a chance to function.
In a successful bone marrow transplant, the new bone marrow migrates to the
large bone cavities (breast bone, skull, hips, ribs, and spine), engrafts and
begins producing normal blood cells. A bone marrow transplant does not ensure
that the disease will not recur; however, it can increase the chances of a cure
or at least prolong the amount of time the patient is disease-free.
Top
Bone
Marrow Transpalntation
The
decision to prescribe a bone marrow transplant is always made on an individual
basis. Your doctor will consider your age, general physical condition, diagnosis,
and stage of the disease. Your doctor will also make sure you understand the
potential benefits and risks of the transplant procedure.
Where does the transplanted bone marrow come from?
Bone marrow given during a transplant either comes from yourself (autologous)
or from a donor whose bone marrow matches your (allogeneic).
Autologous bone marrow transplants
An
autologous bone marrow transplant involves harvesting your own bone marrow,
preserving and storing it in frozen form, and later, after high-dose chemotherapy
and/or radiation therapy, infusing it back into your body. Autologous bone
marrow transplants are possible if the disease affecting the bone marrow is in
remission, or if the condition being treated doesn't involve the bone marrow (as
in breast cancer).
Allogeneic bone marrow transplants
An
allogeneic bone marrow transplant involves harvesting bone marrow from a family
member or an unrelated donor. The harvested marrow is transplanted after you
have received high-dose chemotherapy and/or radiation therapy. Whether the bone
marrow donor is related or not, it must perfectly match your bone marrow.
The matching process is called human leukocyte antigen testing (HLA testing).
A series of blood tests evaluate the compatibility or closeness of tissue
between the donor and recipient. These test results are used to identify and
compare information about your antigens (the markers in cells that stimulate
antibody production) so the tissue typing lab can match a bone marrow transplant
donor to you.
Before the transplant
A
number of tests are performed before the bone marrow transplant procedure to
make sure you are physically able to undergo a transplant. These tests also help
the transplant team identify and treat any potential problems before the
transplant.
Your heart, lungs, and kidney function will be tested. Blood tests, possibly a
CAT scan, and a bone marrow biopsy may also be ordered by your physician. A
complete dental examination is required before the procedure to minimize your
risk of infection, and other precautions will be taken as necessary to minimize
the risk of infection.
The tests required before the bone marrow transplant are usually done on an
outpatient basis. Your transplant coordinator will help arrange these tests for
you.
Central venous catheter placement
Before the bone marrow transplant
can be performed, a central venous catheter is inserted through a vein in your
chest during a simple surgical procedure. A central venous catheter is a
slender, hollow, flexible tube (catheter) that allows fluids, nutrition
solutions, antibiotics, chemotherapy, or blood products to be delivered directly
into your bloodstream without frequently having to insert a needle into your
vein. The catheter can also be used to collect blood samples.
Stimulating your white blood cells
Colony-stimulating factors are
given before your bone marrow transplant to help your white blood cells recover
from chemotherapy and reduce your risk of infection. They also increase the
number of stem cells in your blood. Colony-stimulating factors are hormone-like
drugs that stimulate your white blood cells to multiply, mature, and function.
Colony-stimulating factors are injected directly into your vein through an IV
(intravenously) or injected into the tissue between your skin and muscle (subcutaneously)
using a needle and syringe. You may need to learn how to give subcutaneous
injections to yourself.
Bone marrow harvesting
Bone marrow is withdrawn through a needle
inserted into a bone in the hip. This procedure is performed in the operating
room and the patient is given general anesthesia (pain-relieving medication that
puts you to sleep). If your own bone marrow can not be used for transplantation
and if a donor is not found, peripheral stem cells may be harvested from your
circulating blood.
Top
Chemotherapy and/or radiation therapy
Very high doses of
chemotherapy and/or radiation therapy are given to destroy the abnormal stem
cells and blood cells. They are also given to prepare your body to receive the
bone marrow transplant.
The high dose therapy has a rigorous effect on your body, wiping out your
normal bone marrow. As a result, your blood counts (number of red blood cells,
white blood cells, and platelets) quickly fall to low levels.
During this phase of treatment, you will be given intravenous fluids to flush
out your kidneys and minimize the damage from chemotherapy. You will also be
given medications to control nausea, since chemotherapy often causes nausea and
vomiting.
Because you are in a fragile state of health and do not have enough white
blood cells to protect you from infection, you will be isolated in your hospital
room until after the new bone marrow begins to grow. Your health care providers
will give you specific guidelines about the isolation procedure.
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