Leukemia
is a type of cancer that starts in blood-forming tissue, like the bone marrow. It
causes many abnormal blood cells to be produced and flow in the bloodstream. Each year in the United States, more than
40,800 adults and 3,500 children learn they have this disease. In 2013 alone, there have been around 48,600
new cases, and 23,700 deaths.
Most
blood cells develop from stem cells in the bone marrow. Stem cells turn into
different kinds of blood cells. White blood cells fight infections (there are different
types of white blood cells), red blood cells carry oxygen to body tissues, and platelets
help control bleeding by forming blood clots. When cells get old or damaged,
they die, and are replaced by new cells.
Leukemia Cells
In
a person with leukemia, the bone marrow makes abnormal white blood cells (leukemia
cells), which don't die when they should. They block the normal flow and this
makes it hard for normal blood cells to do their work.
There
are two kinds of leukemia, chronic, and acute. Chronic leukemia usually gets worse slowly. At first, leukemia cells can still do some of
the work of normal white blood cells. As the number of leukemia cells in the
blood increases, people get mild symptoms that eventually worsen. Acute
leukemia usually worsens quickly because the number of leukemia cells
increases rapidly, and the white blood cells can’t do their work.
Leukemia
types can also be grouped based on the type of white blood cells that are
affected:
a)
Lymphoid cells- lymphoid, lymphocytic, or lymphoblastic leukemia.
b)
Myeloid cells- myeloid, myelogenous, or myeloblastic leukemia.
There
are four common types of leukemia:
Chronic lymphocytic
leukemia (CLL):
CLL affects lymphoid cells and usually grows slowly. There are more than 15,000
new cases of CLL each year. Most people with this disease are over age 55.
Chronic myeloid leukemia
(CML): CML
affects myeloid cells and usually grows slowly at first. There are about 5,000
new cases of CML each year. It usually affects adults.
Acute lymphocytic
(lymphoblastic) leukemia (ALL):
ALL affects lymphoid cells and grows quickly. There are more than 5,000 new
cases of ALL each year. This type of leukemia is the most common in young
children. It also affects adults.
Acute myeloid leukemia
(AML): AML
affects myeloid cells and grows quickly. There are more than 13,000 new cases
of AML each year. It affects adults and children.
Hairy cell leukemia is a rare type of chronic
leukemia. Rare leukemias affect less than 6,000 people each year.
Leukemia, like most cancers, is not contagious.
The specific causes of leukemia are unknown, but some factors increase the
chance of getting this disease. Many people who have risk factors never develop
the disease.
- Being exposed to very
high levels of radiation
(atomic bomb explosions, radiation therapy, x-rays/CT scans) may lead to
acute myeloid leukemia, chronic myeloid leukemia, or acute lymphocytic
leukemia.
- Smoking cigarettes increases
the risk of acute myeloid leukemia.
- Exposure to benzene (cigar smoke, chemical
industry, and gasoline) can cause acute myeloid leukemia. It may also
cause chronic myeloid leukemia or acute lymphocytic leukemia.
- Cancer patients
treated with cancer-fighting drugs (i.e. chemotherapy) may get acute myeloid leukemia or acute
lymphocytic leukemia.
- Down
syndrome and other inherited diseases increase the risk of developing acute
leukemia.
- Myelodysplastic
syndrome and other blood disorders are more at risk of acute myeloid
leukemia.
- People with human T-cell leukemia virus type I (HTLV-I) infection are at
increased risk of adult T-cell leukemia (rare).
- Family history of leukemia: Normally only one person in the family gets leukemia. When more people have it (rare), it is probably chronic lymphocytic leukemia.
Symptoms
Like
all blood cells, leukemia cells travel through the body. The symptoms of
leukemia depend on the number of leukemia cells and where these cells collect
in the body.
People
with chronic leukemia may not have symptoms. The doctor may find the disease
during a routine blood test.
People
with acute leukemia usually go to their doctor because they feel sick. If the
brain is affected, they may have headaches, vomiting, confusion, loss of muscle
control, or seizures. Leukemia also can affect other parts of the body such as
the digestive tract, kidneys, lungs, heart, or testes.
Common
symptoms of chronic or acute leukemia may include:
- Swollen lymph nodes
that usually don't hurt (especially in the neck or armpit)
- Fevers or night sweats
- Frequent infections
- Feeling weak or tired
- Bleeding and bruising
easily (bleeding gums, purplish patches in the skin, or tiny red spots
under the skin)
- Swelling or discomfort
in the abdomen (from a swollen spleen or liver)
- Weight loss for no
known reason
- Pain in the bones or joints
Diagnosis
Specialists
who treat leukemia include hematologists, medical oncologists, and radiation
oncologists. Pediatric oncologists and hematologists treat childhood leukemia. Doctors
may perform one or more of the following tests depending on the symptoms and
type of leukemia.
- Physical exam: Your doctor checks
for swollen lymph nodes, spleen, or liver.
- Blood tests: The lab does a
complete blood count to check the number of white blood cells, red blood
cells, and platelets. Leukemia causes a very high level of white blood
cells. It may also cause low levels of platelets and hemoglobin, which is
found inside red blood cells.
- Biopsy: Doctors remove
tissue to look for cancer cells. A biopsy is the only sure way to know
whether leukemia cells are in the bone marrow. Before the sample is taken,
local anesthesia is used to numb the area. This helps reduce the pain. The
doctor removes some bone marrow from the hipbone or another large bone. A
pathologist uses a microscope to check the tissue for leukemia cells.
There are two ways doctors can obtain bone marrow.
- Bone
marrow aspiration:
The doctor uses a thick, hollow needle to remove samples of bone marrow.
- Bone marrow biopsy: The doctor uses a very thick, hollow needle to remove a small piece of bone and bone marrow.
Other
tests are chest x-rays, spinal tap, & cytogenetics.
Treatment
People
with leukemia have many treatment options. Treatments depend on the type of
leukemia (acute or chronic), age, and whether leukemia cells were found in cerebrospinal
fluid.
People
with acute leukemia need to be
treated right away. The goal of treatment is to destroy signs of leukemia in
the body and make symptoms go away (remission). After people go into remission,
more therapy may be given to prevent a relapse (consolidation/maintenance
therapy). Many people with acute leukemia can be cured.
When
treatment for chronic leukemia is needed, it usually controls the disease and
its symptoms. Sometimes people receive maintenance therapy to help keep the
cancer in remission. Chronic leukemia can rarely be cured with chemotherapy,
while stem cell transplants still have a chance to cure it.
Watchful
Waiting
People
with chronic lymphocytic leukemia that don’t have symptoms can put off cancer
treatment to avoid the side effects until they have symptoms. This choice has
risks; it may reduce the chance to control leukemia before it gets worse.
Chemotherapy
uses drugs to destroy leukemia cells. Chemotherapy is usually given in cycles.
Each cycle has a treatment period followed by a rest period.
There are different methods:
- By mouth (pills)
- Into a vein (IV)
- Through a catheter
(a thin, flexible tube) placed in a large
vein, often in the upper chest.
- Into the cerebrospinal fluid: If the pathologist finds leukemia cells in the fluid that fills the spaces in and around the brain and spinal cord, the doctor may order intrathecal chemotherapy. The doctor injects drugs directly into the cerebrospinal fluid, or under the scalp through a special catheter called an ommaya reservoir.
- Blood cells
- Cells in hair roots (hair loss)
- Cells that line the digestive tract (nausea, vomiting, etc.)
- Sperm or egg cells (infertility)
Biological Therapy
Biological therapy improves the body's natural defenses against the disease.Monoclonal antibody (given by IV infusion) binds to leukemia cells. One kind of monoclonal antibody carries a toxin that kills the leukemia cells. Another kind helps the immune system destroy leukemia cells.
Interferon is used for people with chronic myeloid leukemia. It is injected under the skin or into a muscle. It can slow the growth of leukemia cells.
Biological therapies usually cause a rash or swelling where it is injected. It could also cause headaches, muscle aches, fevers, weakness, or anemia.
Radiation Therapy
Radiation therapy (also called radiotherapy) uses high-energy rays to kill leukemia cells. Many people receive radiation to the spleen, brain, or other part of the body where leukemia cells have collected. This therapy occurs 5 days a week for several weeks. Other people receive radiation to the whole body. The radiation treatments are given once or twice a day for a few days, usually before a stem cell transplant. The side effects of radiation therapy depend on the dose of radiation and the part of the body that is treated.Stem Cell Transplant
A stem cell transplant allows for high doses of drugs, and/or radiation. Because the treatments destroy leukemia cells and normal blood cells, healthy stem cells are injected through a large vein afterwards, to replace the cells that were destroyed. Stem cells may come from oneself (before treatment they are stored), an unrelated donor, a parent, a sibling, or from an identical twin. Stem cells usually come from the blood or from the bone marrow; they may also come from an umbilical cord blood transplant. Over time, the stem cells that were transplanted will start producing healthy blood cells. Graft-vs.-host disease (GVHD) may occur when the donated white blood cells in the stem cell graft react against the patient's normal tissues. It is usually the liver, skin, or digestive tract that is affected. GVHD may occur even years after the transplant.
(http://www.cancer.gov/cancertopics/wyntk/leukemia) & picture taken from yahoo images.
