Pleural mesothelioma is of two kinds: (1) diffuse and malignant
(cancerous), and (2) localized and benign (non-cancerous.)
Benign mesothelioma can often be removed surgically, are generally not
life-threatening, and are not usually related to asbestos exposure.
Malignant mesothelioma, however, are very serious. Fortunately, they are
rare - about two thousand people are diagnosed with mesothelioma in the
U.S. each year.
The remainder of this section is about diffuse malignant pleural
Pleural mesothelioma is a cancer of the cells that make up the pleura or
lining around the outside of the lungs and inside of the ribs. Its only
known cause in the U.S. is previous exposure to asbestos fibers, including
chrysotile, amosite or crocidolite. This exposure is likely to have
happened twenty or more years before the disease becomes evident, since it
takes many years for the disease to "incubate." It is the most common type
of mesothelioma, accounting for about 75% of all cases.
Mesothelioma is sometimes diagnosed by coincidence, before there are any
symptoms. For instance, tumors have been discovered through routine chest
x-rays. However, when symptoms occur, they may include shortness of
breath, weakness, weight loss, loss of appetite, chest pains, lower back
pains, persistent coughing, difficulty in swallowing, alone or in
combination. An initial medical examination often shows a pleural
effusion, which means an accumulation of fluid in the pleural space - the
area between the lungs and the chest wall.
The first step in detecting pleural mesothelioma is, typically, a chest
x-ray or CT scan. This is often followed by a bronchoscopy, using a
viewing scope to look inside the lungs.
The actual diagnosis usually requires obtaining a piece of tissue through
a biopsy. This could be a needle biopsy, an open biopsy, or through a tube
with a camera (thoracoscopy or chest scope.) If an abnormality is seen
through the camera then a tissue sample can be taken at the same time,
using the same tube. This is a hospital procedure that requires
anesthesia, but is not usually painful. The tissue sample is tested by a
Fluid build-up from the pleural effusion can generally be seen on a chest
x-ray and heard during a physical examination, but a firm diagnosis of
mesothelioma can only be made through a biopsy and pathological testing.
This is important because there are also benign pleural effusions and
other tumors that have a similar appearance to mesothelioma. Diagnosing
mesothelioma can be quite difficult; it requires special lab stains, and
much experience in understanding them.
The spread of the tumor over the pleura causes pleural thickening. This
can reduce the flexibility of the pleura and encase the lungs in an
increasingly restrictive girdle. With the lungs restricted, they get
smaller and less functional, and breathing becomes more difficult. At
first a person with mesothelioma may be breathless only when he or she
exercises, but as lung function drops, he or she can become short of
breath even while resting.
The tumor spreads by direct invasion of surrounding tissue. As it spreads
inward it can compress the lungs. As the tumor spreads outward it can
invade the chest wall and ribs, and this can be extremely painful.
Current medical science does not know exactly how and why, at a cellular
level, asbestos fibers cause mesothelial cells to become abnormal
(malignant or cancerous.) Thus it is not known whether only one fiber
causes the tumor or whether it takes many fibers. It seems that asbestos
fibers in the pleura can start a tumor as well as promote its growth; the
tumor does not depend on any other processes for its development.
There is as yet no known cure for malignant mesothelioma. The prognosis
depends on various factors, including the size and stage of the tumor, the
extent of the tumor, the cell type, and whether or not the tumor responds
to treatment. KMESA has represented many clients who lived for five to ten
years after diagnosis, most of them in good health for a majority of those
years. Some mesothelioma victims succumb within a few months; the average
survival time is about a year.
The treatment options for people with mesothelioma have improved
significantly, especially for those whose cancer is diagnosed early and
treated vigorously. Many people are treated with a combination of
therapies, sometimes known as multimodal therapy.
Specific types of treatment include:
- Chemotherapy and other drug-based therapies
- Radiation therapy
- Surgery and
- Intra-operative photodynamic therapy
There are also experimental treatments like gene therapy and
immunotherapy, angiogenesis inhibitors, and clinical trials for various
new treatments and combinations of treatments.
Treatments that reduce pain and improve lung function, are becoming more
successful (although they cannot cure mesothelioma.) Pain control
medications have become easier to administer. Debulking is a surgical
process of removing a substantial part of the tumor and reducing the
pleural thickening; this can provide significant relief. X-ray therapy has
also been successfully used to control the tumor and the pain associated
with it for a while.
Definition: A noncancerous tumor of the pleura (lining of the lung and chest cavity).
Causes, incidence, and risk factors:
Nonmalignant mesothelioma is usually a localized tumor that affects men
more frequently than women. The tumor may grow to a large size and
compress the lung, causing the symptoms of shortness of breath.
- chronic cough
- shortness of breath
- chest pain
Signs and tests:
A physical examination reveals the clubbed appearance of the fingers.
Tests that may show benign mesothelioma:
- chest X-ray
- CT scan of the chest
- open lung biopsy
- Surgery is indicated for a solitary tumor.
- The outcome is expected to be good with prompt treatment.
- Pleural effusion (fluid escaping into the membranes around the lungs) is a
Calling your health care provider:
Call for an appointment with your health care provider if you notice a
chroniccough or other signs of mesothelioma.
- There is no known prevention for this very rare disorder.