Mesothelioma is a rare form of cancer in which malignant cells are found in the mesothelium, a protective sac that covers most of the body's internal organs. Most people who develop mesothelioma have worked in places where they inhaled asbestos.
What is mesothelioma?
Mesothelioma 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
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.
What are risk factors for mesothelioma?
Being exposed to 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 mesothelioma 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 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. Exposure to asbestos increases the risk of lung cancer, asbestosis , and other cancers.
Smoking does not appear to increase the risk of mesothelioma.
Who is at increased risk for developing mesothelioma?
Since the early 1940s, millions of
American workers have been exposed to asbestos. 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, and other tradespeople. Today,
the U.S. Occupational Safety and Health Administration 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 mesothelioma exposure.
The risk of mesothelioma and asbestos-related disease increases with heavier exposure to asbestos and longer exposure time. However, some individuals with only brief exposures have developed mesothelioma.
There is some evidence that family members and others living with asbestos workers have an increased risk of developing mesothelioma. 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 mesothelioma, 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.
How is mesothelioma diagnosed?
Diagnosing mesothelioma is often difficult, because the symptoms are similar
to those of a number of other conditions.
A complete physical examination may be performed, including x-rays of the
chest or abdomen and lung function tests. A CT scan or an MRI may
also be useful to diagnose mesothelioma. 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.
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 mesothelioma has spread and, if so, to which parts of the body. Knowing the stage of the disease helps the doctor plan treatment.
How is mesothelioma treated?
Mesothelioma treatment depends on the location of the cancer, the stage
of the disease, and the patient's age and general health. Standard mesothelioma 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).
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.
People considering clinical trials may be interested in the NCI booklet Taking Part in Clinical Trials: What Cancer Patients Need To Know. This booklet describes how research studies are carried out and explains their possible benefits and risks. The booklet is available by calling the CIS, or from the NCI Publications Locator Web site at http://www.cancer.gov/publications on the Internet.
Copyright 2004 Mesothelioma Greatnow All rights Reserved
Since the early 1930s, millions of Americans have been exposed to asbestos. Health hazards from asbestos have been recognized in workers exposed in shipbuilding trades, asbestos mining and milling, manufacturing of asbestos textiles and other asbestos products and a variety of other trades. Demolition workers, drywall removers, and firefighters also may be exposed to asbestos fibers. As a result of Government regulations and improved work practices, today’s workers are likely to face smaller risks than did those exposed in the past.
Individuals who have been exposed to
asbestos fibers on the job or at home via a family contact should inform their
physician of their exposure history and any symptoms. Asbestos fibers can
be measured in urine, feces, mucus, or material rinsed out of the lungs. A
thorough physical examination, including a chest x-ray and lung function tests,
may be recommended. It is important to note that chest x-rays cannot detect
asbestos fibers in the lungs, but they can help identify any lung changes
resulting from asbestos exposure. Interpretation of the chest x-ray may require
the help of a specialist who is experienced in reading x-rays for asbestos-related
diseases. Other tests also may be necessary.
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