3. 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.
4. 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.
5. 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.
6. 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.
7. 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. Staging 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.
8. 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.
9. Are new treatments for mesothelioma being studied?
Yes. Because mesothelioma is very hard to control, the National
Cancer Institute (NCI) is sponsoring clinical trials (research
studies with people) that are designed to find new treatments and
better ways to use current treatments. Before any new treatment can
be recommended for general use, doctors conduct clinical trials to
find out whether the treatment is safe for patients and effective
against the disease. Participation in clinical trials is an
important treatment option for many patients with mesothelioma.
Information supplied by
National Cancer Institute
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