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Mesothelioma
Disease
A benign (noncancerous) or malignant (cancerous) tumor affecting
the lining of the chest or abdomen. Exposure to asbestos particles
in the air increases the risk of developing malignant mesothelioma.
- What
is mesothelioma?
Mesothelioma
(cancer of the mesothelium) is a disease in which cells
of the mesothelium become abnormal and divide without
control or order. They can invade and damage nearby tissues
and organs. Cancer cells can also metastasize (spread)
from their original site to other parts of the body. Most
cases of mesothelioma begin in the pleura or peritoneum.
- How
common is mesothelioma?
Although
reported incidence rates have increased in the past 20
years, mesothelioma is still a relatively
rare cancer. About 2,000 new cases of mesothelioma are
diagnosed in the United States each year. Mesothelioma
occurs more often in men than in women and risk increases
with age, but this disease can appear in either men or
women at any age.
- What
are the risk factors for mesothelioma?
Working with
asbestos is the major risk factor for mesothelioma. A
history of asbestos exposure at work is reported in about
70 percent to 80 percent of all cases. However, mesothelioma
has been reported in some individuals without any known
exposure to asbestos.
Asbestos is
the name of a group of minerals that occur naturally as
masses of strong, flexible fibers that can be separated
into thin threads and woven. Asbestos has been widely
used in many industrial products, including cement, brake
linings, roof shingles, flooring products, textiles, and
insulation. If tiny asbestos particles float in the air,
especially during the manufacturing process, they may
be inhaled or swallowed, and can cause serious health
problems. In addition to mesothelioma, exposure to asbestos
increases the risk of lung cancer, asbestosis (a noncancerous,
chronic lung ailment), and other cancers, such as those
of the larynx and kidney.
Smoking does
not appear to increase the risk of mesothelioma. However,
the combination of smoking and asbestos exposure significantly
increases a person's risk of developing cancer of the
air passageways in the lung.
- Who
is at increased risk for developing mesothelioma?
Asbestos has
been mined and used commercially since the late 1800s.
Its use greatly increased during World War II. Since the
early 1940s, millions of American workers have been exposed
to asbestos dust. Initially, the risks associated with
asbestos exposure were not known. However, an increased
risk of developing mesothelioma was later found among
shipyard workers, people who work in asbestos mines and
mills, producers of asbestos products, workers in the
heating and construction industries, and other tradespeople.
Today, the U.S. Occupational Safety and Health Administration
(OSHA) sets limits for acceptable levels of asbestos exposure
in the workplace. People who work with asbestos wear personal
protective equipment to lower their risk of exposure.
The risk of
asbestos-related disease increases with heavier exposure
to asbestos and longer exposure time. However, some individuals
with only brief exposures have developed mesothelioma.
On the other hand, not all workers who are heavily exposed
develop asbestos-related diseases.
There is some
evidence that family members and others living with asbestos
workers have an increased risk of developing mesothelioma,
and possibly other asbestos-related diseases. This risk
may be the result of exposure to asbestos dust brought
home on the clothing and hair of asbestos workers. To
reduce the chance of exposing family members to asbestos
fibers, asbestos workers are usually required to shower
and change their clothing before leaving the workplace.
- What
are the symptoms of mesothelioma?
Symptoms of
mesothelioma may not appear until 30 to 50 years after
exposure to asbestos. Shortness of breath and pain in
the chest due to an accumulation of fluid in the pleura
are often symptoms of pleural mesothelioma. Symptoms of
peritoneal mesothelioma include weight loss and abdominal
pain and swelling due to a buildup of fluid in the abdomen.
Other symptoms of peritoneal mesothelioma may include
bowel obstruction, blood clotting abnormalities, anemia,
and fever. If the cancer has spread beyond the mesothelium
to other parts of the body, symptoms may include pain,
trouble swallowing, or swelling of the neck or face.
These symptoms
may be caused by mesothelioma or by other, less serious
conditions. It is important to see a doctor about any
of these symptoms. Only a doctor can make a diagnosis.
- How
is mesothelioma diagnosed?
Diagnosing
mesothelioma is often difficult, because the symptoms
are similar to those of a number of other conditions.
Diagnosis begins with a review of the patient's medical
history, including any history of asbestos exposure. A
complete physical examination may be performed, including
x-rays of the chest or abdomen and lung function tests.
A CT (or CAT) scan or an MRI may also be useful. A CT
scan is a series of detailed pictures of areas inside
the body created by a computer linked to an x-ray machine.
In an MRI, a powerful magnet linked to a computer is used
to make detailed pictures of areas inside the body. These
pictures are viewed on a monitor and can also be printed.
A biopsy is
needed to confirm a diagnosis of mesothelioma. In a biopsy,
a surgeon or a medical oncologist (a doctor who specializes
in diagnosing and treating cancer) removes a sample of
tissue for examination under a microscope by a pathologist.
A biopsy may be done in different ways, depending on where
the abnormal area is located. If the cancer is in the
chest, the doctor may perform a thoracoscopy. In this
procedure, the doctor makes a small cut through the chest
wall and puts a thin, lighted tube called a thoracoscope
into the chest between two ribs. Thoracoscopy allows the
doctor to look inside the chest and obtain tissue samples.
If the cancer is in the abdomen, the doctor may perform
a peritoneoscopy. To obtain tissue for examination, the
doctor makes a small opening in the abdomen and inserts
a special instrument called a peritoneoscope into the
abdominal cavity. If these procedures do not yield enough
tissue, more extensive diagnostic surgery may be necessary.
If the diagnosis
is mesothelioma, the doctor will want to learn the stage
(or extent) of the disease. Stging involves more tests
in a careful attempt to find out whether the cancer has
spread and, if so, to which parts of the body. Knowing
the stage of the disease helps the doctor plan treatment.
Mesothelioma
is described as localized if the cancer is found only
on the membrane surface where it originated. It is classified
as advanced if it has spread beyond the original membrane
surface to other parts of the body, such as the lymph
nodes, lungs, chest wall, or abdominal organs.
- How
is mesothelioma treated?
Treatment for
mesothelioma depends on the location of the cancer, the
stage of the disease, and the patient's age and general
health. Standard treatment options include surgery, radiation
therapy, and chemotherapy. Sometimes, these treatments
are combined.
- Surgery
is a common treatment for mesothelioma. The doctor may
remove part of the lining of the chest or abdomen and
some of the tissue around it. For cancer of the pleura
(pleural mesothelioma), a lung may be removed in an
operation called a pneumonectomy. Sometimes part of
the diaphragm, the muscle below the lungs that helps
with breathing, is also removed.
- Radiation
therapy, also called radiotherapy, involves the
use of high-energy rays to kill cancer cells and shrink
tumors. Radiation therapy affects the cancer cells only
in the treated area. The radiation may come from a machine
(external radiation) or from putting materials that
produce radiation through thin plastic tubes into the
area where the cancer cells are found (internal radiation
therapy).
- Chemotherapy
is the use of anticancer drugs to kill cancer cells
throughout the body. Most drugs used to treat mesothelioma
are given by injection into a vein (intravenous, or
IV). Doctors are also studying the effectiveness of
putting chemotherapy directly into the chest or abdomen
(intracavitary chemotherapy).
To
relieve symptoms and control pain, the doctor may use
a needle or a thin tube to drain fluid that has built
up in the chest or abdomen. The procedure for removing
fluid from the chest is called thoracentesis.
Removal of fluid from the abdomen is called paracentesis.
Drugs may be given through a tube in the chest to prevent
more fluid from accumulating. Radiation therapy and surgery
may also be helpful in relieving symptoms.
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