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All About Mesothelioma
Mesothelioma
is a cancer of mesothelial cells. These cells form a lining that covers the
outer surface of most of our internal body organs. These linings are sometimes
called mesothelium. This disease is almost caused by previous exposure of
asbestos. Most people who develop mesothelioma have worked on jobs where they
inhaled asbestos particles, or have been exposed to asbestos dust and fibre in
other ways, such as by washing the clothes of a family member who worked with
asbestos, or by home renovation using asbestos cement products. Unlike lung
cancer, there is no association between mesothelioma and smoking.
Its most common site is
the pleura (outer lining of the lungs and chest cavity), but it may also occur
in the peritoneum (the lining of the abdominal cavity) or the pericardium (a sac
that surrounds the heart).
Mesothelioma that affects
the pleura can cause these signs and symptoms:
* chest wall pain
* pleural effusion, or
fluid surrounding the lung
* shortness of breath
* fatigue or anemia
* wheezing, hoarseness,
or cough
* blood in the sputum
(fluid) coughed up
Tumors that affect the
abdominal cavity often do not cause symptoms until they are at a late stage.
Symptoms include:
* abdominal pain
* ascites, or an abnormal
buildup of fluid in the abdomen
* a mass in the abdomen
* problems with bowel
function
* weight loss
In severe cases of the
disease, the following signs and symptoms may be present:
* blood clots in the
veins, which may cause thrombophlebitis
* disseminated
intravascular coagulation, a disorder causing severe bleeding in many body
organs
* jaundice, or yellowing
of the eyes and skin
* low blood sugar level
* pleural effusion
* pulmonary emboli, or
blood clots in the arteries of the lungs
* severe ascites
Diagnosis
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. A history of exposure to asbestos may increase clinical suspicion for
mesothelioma. A physical examination is performed, followed by chest X-ray and
often lung function tests. The X-ray may reveal pleural thickening commonly seen
after asbestos exposure and increases suspicion of mesothelioma. A CT (or CAT)
scan or an MRI is usually performed. If a large amount of fluid is present,
abnormal cells may be detected by cytology if this fluid is aspirated with a
syringe.
If cytology is positive
or a plaque is regarded as suspicious, a biopsy is needed to confirm a diagnosis
of mesothelioma. A doctor 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.
If the cancer is in the
abdomen, the doctor may perform a laparoscopy. To obtain tissue for examination,
the doctor makes a small opening in the abdomen and inserts a special instrument
into the abdominal cavity. If these procedures do not yield enough tissue, more
extensive diagnostic surgery may be necessary.
Treatment
Treatment of MM using
conventional therapies has not proved successful and patients have a median
survival time of 6 - 12 months after presentation.
Surgery
Surgery, either by itself
or used in combination with pre- and post-operative adjuvant therapies has
proved disappointing. A pleurectomy/decortication is the most common surgery, in
which the lining of the chest is removed. Less common is an extrapleural
pneumonectomy (EPP), in which the lung, lining of the inside of the chest, the
hemi-diaphragm and the pericardium are removed. It is not possible to remove the
entire mesothelium without killing the patient.
Radiation
For patients with
localized disease, and who can tolerate a radical surgery, radiation is often
given post-operatively as a consolidative treatment. The entire hemi-thorax is
treated with radiation therapy, often given simultaneously with chemotherapy.
Risk factors
Working with asbestos is
the major risk factor for mesothelioma. A history of asbestos exposure exists in
almost all cases. However, mesothelioma has been reported in some individuals
without any known exposure to asbestos. In rare cases, mesothelioma has also
been associated with irradiation, intrapleural thorium dioxide (Thorotrast), and
inhalation of other fibrous silicates, such as erionite.The combination of
smoking and asbestos exposure significantly increases a person's risk of
developing cancer of the airways (lung cancer, bronchial carcinoma).
Some studies suggest that
simian virus 40 (SV40) may act as a cofactor in the development of mesothelioma.
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