Mesothelioma-Asbestos In My Body?
Mesothelioma is a cancer which is linked to exposure to
asbestos fibers in 70 to 80 percent of cases. The National
Cancer institute defines malignant mesothelioma as "a rare form
of cancer...a disease in which cancer (malignant) cells are
found in the sac lining the chest (the pleura), the lining of
the abdominal cavity (the peritoneum) or the lining around the
heart (the pericardium)." It is one of the most deadly cancers
known to man; the average life span of an afflicted person from
the time of diagnosis until death is less than 24 months.
Mesothelioma developes in approximately 3,000 United States
citizens every year. Most of those diagnosed have a history of
occupational exposure to asbestos, though a few have
environmental or household contact. This cancer has an extremely
long latency period; an exposure period of as little as one or
two months can result in a mesothelioma up to 50 years later.
Patients who had contact with asbestos as far back as the 1940s
are now being diagnosed with this disease. In fact, the average
time between exposure and the development of mesothelioma is
35-40 years.
When asbestos first came into use, its risks were unknown, and
it was widely used as a fire-retardant material. Many people
worked with this deadly substance, unaware that it would kill
them several decades later. Workers such as bricklayers,
insulaters, plasterers, electricians, mechanics, carpenters, and
other tradesmen were exposed to asbestos on a daily basis as it
was contained in many insulation and construction materials.
Even occassional exposure to asbestos is a health risk, and
there have been many cases of mesothelioma developing in
patients who only had brief contact, such as wives of
asbestos-exposed workers who washed their husbands' overalls.
Due to the long latency period and vague, diffuse initial
symptoms, there is often a delay in accurate diagnosis. As with
many cancers, early symptoms can be mild and non-specific. Often
patients present with only shortness of breath and a persistent
cough; some show no symptoms at all in the initial stages, and
the disease is first noticed on a routine chest X-ray. One early
tell-tale sign is pleural effusion, a collection of fluid in the
lungs. The right lung is affected 60% of the time, bilateral
involvement being seen in 5% of cases. Less common initial
complaints due to lung mesothelioma are fever, night sweats,
weight loss, a raspy voice and facial swelling. Peritoneal
mesothelioma can cause abdominal symptoms such as pain,
abdominal swelling, nausea, weight loss, bowel obstruction,
anemia and swelling of the feet. As the disease progresses,
patients often develop severe cachexia (wasting).
One of the most common symptoms of mesothelioma, pleural
effusion, is an accumulation of fluid between the parietal
pleura, which covers the chest wall and diaphragm, and the
visceral pleura, which covers the lungs. Both membranes are
covered with mesothelial cells which, under normal conditions,
produce a small amount of fluid that acts as a lubricant between
the chest wall and the lung. Any excess fluid is removed via
blood and lymph vessels, thus maintaining a balance. When more
fluid is produced than can be absorbed, an effusion forms.
These effusions are called either transudates and exudates. A
transudate is a clear fluid that forms not because the pleural
surfaces are diseased, but because of an imbalance between the
normal production and removal of the fluid. Often this is caused
by congestive heart failure. An exudate, which contains many
cells and proteins and is often cloudy in color, results from
disease of the pleura itself, and is common to mesothelioma. To
differentiate between a transudate or an exudate, a diagnostic
thoracentesis, in which a needle or catheter is used to obtain a
fluid sample, may be conducted.
As the volume of excess fluid increases, symptoms develop such
as shortness of breath (dyspnea) , chest pain, or a
non-productive dry cough. Heard through a stethoscope, normal
breath sounds are muted, and tapping on the chest will reveal
dull rather than hollow sounds.
A pleural effusion can be seen with a chest X-ray, ultrasound or
CT scan. Since pleural effusions are often caused by congestive
heart failure, the discovery of an effusion is not in itself
immediately suggestive of a malignant process.
A histological examination of pleural fluid is negative in 85%
of cases; a definitive diagnoses is more often is obtained by a
needle biopsy or surgical biopsy of pleural tissue.
Symptomatic treatment of lung compression caused by effusion is
accomplished by application of a sclerosing agent which
eliminates the space between the lung and the chest cavity, a
process called chemical pleurodesis. Talc is usually used, with
a success rate of 95%. It can be administered either as a powder
or as a slurry mixed with saline. A surgical team opens the
chest wall, removes the effusion, then collapses the lung before
applying the talc. Once the lung is fused to the chest wall, an
effusion can no longer accumulate and compress the lung. This is
strictly a palliative measure to improve the patient's quality
of life, and has no effect on the progression of the disease.
Attemps to cure mesothelioma utilize surgery to remove diseased
tissue, combined with chemo and raiotherapy. Several new
treatment modalities are currently being investigated. These
include Photodynamic therapy, which uses light of particular
frequencies to target and kill cancer cells which, compared to
normal tissue, display increased uptake of photosensitizing
drugs; immunotherapy, which fights the abnormal cells through
stimulation of the body's own immune system; and Intensity
Modulated Radiation Therapy, which is a radiation treatment that
attempts to target just the malignancy, thus avoiding damage to
adjacent healthy cells and tissue. In addition, some success has
been acheived with the chemotherapeutic drug Alitma
(pemetrexed). However, despite the number of clinical trials
currently underway, as of the date of this article the prognosis
for mesothelioma sufferers is still extremely poor.