What
is Peritoneal Mesothelioma? - Symptoms, Development, Diagnosis &
Treatment Options for Peritoneal Mesothelioma
(July 22nd, 2008)
 Peritoneal
Mesothelioma is a malignant cancer that is much rarer than Pleural
mesothelioma. About 100 - 500 cases are diagnosed in the USA each
year, which is about 25% - 30% of all mesothelioma cases. Results
of diagnosis are approximately 54.7% in male versus 45.3% in females,
with an average age of 65 - 69 (Source: SEER - Surveillance, Epidemiology,
and End Results). Symptoms for Peritoneal mesothelioma surface to
life 20 - 30 years after Asbestos exposure, as opposed to Pleural
mesothelioma where symptoms surface to life after 30 - 40 years.
Peritoneal mesothelioma attacks the abdominal lining or Peritoneum
of the lungs, and thus is also known as abdominal mesothelioma.
The peritoneum insulates organs of the abdomen and its primary purpose
is for protection. The image on the left is of the peritoneum consisting
of 2 parts; visceral and parietal peritoneum. The function of the
visceral peritoneum is to cover internal abdominal organs and it
makes up most of the outer layer of the intestinal tract. The parietal
peritoneum (outer layer) on the other hand insulates the abdominal
cavity and is attached to the abdominal wall. The space between
these two layers is known as the peritoneal cavity, filled with
a 50ml serous fluid that allows the 2 layers to freely slide and
glide over each other. Another purpose for the serous fluid is to
help the intestines move food freely throughout the body. Cancerous
cells force the peritoneal cavity to overproduce the serous fluid
causing an excessive buildup of fluids in the abdominal cavity.
This is also known as ascites.
Development of Peritoneal Mesothelioma
 Just
like Pleural mesothelioma, the single most important factor for
development of Peritoneal mesothelioma is exposure to Asbestos.
The process of how tissues in the lungs become malignant or cancerous
(the carcinogenic process) is not fully understood by doctors yet.
After inhalation of asbestos fibers at workplaces, they cannot be
removed by the body's immune system because of their durability.
Over a period of time, they cause chronic inflammation of cells
in the lungs and develop a fibrosis that stop the peritoneum from
functioning properly and protecting abdominal organs. The main difference
between pleural & peritoneal mesothelioma is how asbestos fibers
penetrate into the peritoneum. Scientists predict there are 3 ways
this can happen:
i) Inhaled asbestos fibers are transported through the lymphatic
system to the peritoneal cavity (space between the parietal &
visceral peritoneum layers). The image above is of the lymphatic
system where the black markers are primary translocators of asbestos
fibers into the lungs, while the white markers are secondary translocators
of asbestos fibers. The diagram shows how asbestos fibers can travel
through the lymphatic system starting from the alveolar space or
the pulmonary cap into the pleural space.
ii) Asbestos fibers entered the body through foods & drinks
that asbestos workers had whilst on the job. Asbestos dust &
fibers in the air is common among workplaces such as factories,
shipyards & metal works.
iii) Asbestos fibers are carried into the abdominal cavity &
lining by being broken down into smaller pieces and transported
through the bloodstream.
Diagnosis & Staging of Peritoneal Mesothelioma
 Diagnosis
of Peritoneal mesothelioma is very difficult, if not impossible.
Computed Tomography (CT) scans are commonly used to distinguish
between the two types of peritoneal mesothelioma; "dry"
or "wet". What's interesting is that the image that CT
scans produce can vary significantly. In the "dry" type
of photos, CT scans reveal small localized masses of tumors with
no fluids (ascites). In the "wet" type, CT scans reveal
widespread masses of tumors with presence of fluids (ascites). Doctors
can then order a removal of fluids from the abdomen via a process
called paracentesis. The image on the left is of the Pelvis showing
large volumes of free ascites (fluids in the lungs or abdomen).
These fluids can then be removed via a process called pleural effusions.
As for Staging Peritoneal mesothelioma, there is no set system
that can stage the extent of how far the tumor has spread. However,
it is staged using the TNM system which is the most common cancer
staging system. TNM stands for tumor (T), lymph nodes (N) and metastases
(M). Peritoneal mesothelioma can also be detected in 'Stages'.
- Stage 1: Shows a tumor or wound that that can be completely removed
from the surface of the lungs.
- Stage 2: Shows the tumor contained in the abdominal cavity or
in the peritoneal cavity where some portion of it can be removed
but not all.
- Stage 3: Shows tumor in the abdominal cavity where organs such
as the liver or colon are damaged.
- Stage 4: Shows tumors that have extended outside the abdominal
cavity.
Symptoms of Peritoneal Mesothelioma
Symptoms of Peritoneal mesothelioma are closely associated with
symptoms of other diseases such as gallbladder problems, hernia
or pelvic mass. Here is a list of the typical symptoms:
- Fever
- Weight loss
- Anemia
- Abdominal mass and abdominal pain
- Distention (spreading & stretching in all directions) of the
abdomen
- Fluids in the abdomen (ascites)
- Weight loss
- Digestion problems
When a doctor diagnoses peritoneal mesothelioma, usually the tumor
has grown to very advanced stages because its symptoms are easily
associated with symptoms of other common diseases. Advanced stages
of peritoneal malignant mesothelioma often means multiple tumors
have invaded the peritoneum and the cancer has spread (metastasized)
to other areas such as the lungs, lymph nodes, and the heart.
Treatment of Peritoneal Mesothelioma
Treatment options available for Peritoneal mesothelioma are similar
to what is available for Pleural mesothelioma. Options include Magnetic
Resonance Imaging (MRI), X-Rays or Computed Tomography (CT) scans.
There is no cure for peritoneal mesothelioma however, it does provide
a longer life and a better prognosis than pleural mesothelioma.
After being diagnosed with pleural mesothelioma, a patient can expect
to live for an average of 1 year to 16 months. On the other hand,
a patient diagnosed with Peritoneal mesothelioma can expect to live
for another average of 2 - 5 years.
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