Mesothelioma is
an aggressive cancer affecting the membrane lining of the lungs and abdomen. Malignant mesothelioma is the most serious of all
asbestos-related diseases. The primary cause and risk factor for mesothelioma
is exposure to asbestos.
Making a correct mesothelioma diagnosis is
particularly difficult for doctors because
the disease often presents with symptoms that mimic other common
ailments.
There is no known cure for mesothelioma, but treatments such as surgery
and
chemotherapy have helped to improve the typical mesothelioma prognosis.
Pleural mesothelioma (affecting the lung’s protective lining
in the chest cavity) represents about three quarters of all mesothelioma
incidence. Peritoneal mesothelioma, which affects the abdominal cavity,
and
pericardial mesothelioma, which affects the cardiac cavity, comprise the
remainder.
There are three
recognized mesothelioma cell-types. Between 50 and 70% of all mesotheliomas are
of the epithelial variety. While prognosis is generally poor, it is considered
less aggressive than sarcomatoid mesothelioma and biphasic mesothelioma, which
comprise the remainder of cell type diagnoses.
The cavities within the body encompassing the chest,
abdomen, and heart are surround by a membrane of cells known as the
mesothelium. Mesothelial cells assist in general organ functions. The
mesothelium is particularly important to organs that are commonly in motion,
such as expansion or contraction of the lungs, stomach, or heart. Lubrication
from the mesothelial cells allows free range of motion within the body. The
mesothelium of the chest, abdomen, and cardiac cavity are called the pleura,
the peritoneum, and the pericardium, respectively. Each of these groupings of
mesothelial cells is extremely critical to the functions of the body structures
which they encompass.
Malignancies (cancerous tumors) occurring within the
mesothelial membranes are known as malignant mesothelioma, or simply
mesothelioma. Benign tumors of the mesothelium are known to occur, but are much
more rare than malignant mesothelial tumors.
While tumors of the mesothelium were first recognized in the
late 18th century, it was not until the middle of the 20th century that this
particular cancer was studied and examined with more detail. It was at this
time when suspicions of the cancer’s causal relationship with asbestos exposure
became more substantiated. A joint research venture through the Department of
Thoracic Surgery at the University of the Witswater and Johannesburg General
Hospital in South Africa provided the most compelling evidence of the nexus
between asbestos exposure and the development of pleural mesothelioma.
Incidence of mesothelioma is still quite rare, with only
2,500-3000 diagnoses in the United States each year. There was a spike in
reported diagnoses between 1970 and 1984, which has been attributed to the
latency period between diagnosis and the height of industrial exposures, which
occurred roughly 40-60 years prior to this time. Exposure was common in nearly
all industries but was particularly common in the WWII-era military industrial
cycle, including Navy Shipyards.
Although this cancer is much more common in men over the age
of 60 (largely attributed to the industrial exposures within male-dominated
industries), mesothelioma in women and children has been described as well. Mesothelioma
causes for diagnosis in women and children are mainly attributed to secondary
exposure to asbestos, as it was not uncommon for men to bring asbestos back
into the home on their body or clothing if proper cleaning facilities were not
available on site.
Mesothelioma is diagnosed through a comprehensive
combination of biopsy and imaging scans.
Mesothelioma can be a difficult malignancy to diagnose
because the symptoms of the disease closely resemble other respiratory
conditions, and because the pathology can be very difficult to distinguish from
adenocarcinoma of the lung. For this reason, misdiagnosis is not uncommon in
mesothelioma patients. Symptoms of mesothelioma include chest pain, chronic
cough, effusions of the chest and abdomen, and the presence of blood in lung
fluid.
Diagnostic surgeries, including a biopsy, will typically be
required to determine the type of malignant cells that are present in the body.
Typically a body imaging scan, including a magnetic resonance image (MRI),
computer topography (CT scan), and/or positron emission tomography (PET), will
be required to determine the extent and location of the disease.
While mesothelioma is typically advanced at diagnosis,
treatment options are available.
Mesothelioma, while certainly an aggressive disease, is a
manageable malignancy. While there is no cure for the cancer, mesothelioma
treatment options may potentially include surgery, chemotherapy, and radiation
therapy. A combination of Alimta and Cisplatin is currently the only FDA approved
chemotherapy regimen, though several clinical trials are currently in progress
utilizing other drugs including Gemcitabine and Onconase, that may lead to new
treatment options that provide a benefit for patients.
Radiation therapy is also utilized, but typically in
conjunction with other treatment methods like surgery and chemotherapy.
Surgical resection of mesothelioma is possible in early-stage-diagnosed
patients. Diagnostic and palliative procedures such as thoracentesis and
pleurodesis are also commonly performed in patients with malignant mesothelioma
in order to minimize cancer-related symptoms.
Alternative therapies have also been used effectively by
many mesothelioma patients to assist in managing symptoms of the disease and
conventional treatments. Mesothelioma is caused by exposure to asbestos.
Mesothelioma is primarily caused by exposure to asbestos,
though cases have been documented in children or other individuals with no
asbestos history. Asbestos is a microscopic and naturally occurring mineral
that lodges in the pleural lining of the lungs and the peritoneal lining of the
abdominal cavity. In most cases, several years will pass (up to 60) before
mesothelioma develops in those who had been exposed to asbestos.