Malignant peritoneal mesothelioma (MPM) is a rare and aggressive tumor of the peritoneum (the tissue that surrounds the abdomen) and is considered a universally fatal disease. Of all types of mesothelioma, only 20% to 33% arise from the peritoneum itself. Most mesotheliomas commonly originate in the pleura. When the peritoneal cancer spreads, doctors call it diffuse peritoneal mesothelioma.

Peritoneal Mesothelioma Causes

Peritoneal mesothelioma starts when an individual breathes in asbestos fibers, usually as part of their job. Asbestos is a natural mineral that is resistant to heat, fire, and electricity. Until the late 1970s, asbestos was widely used in the automotive, building, fireproofing, roofing, and shipbuilding industries.

Adhesives, ceiling tiles, floor tiles, paint, and numerous plastics contained asbestos. Easily released into the air, asbestos fibers are very small, which makes it very easy for workers to breathe them into their lungs. Today’s industries no longer use asbestos.

The asbestos fibers get into the body and move to the digestive system, slicing through the stomach and intestines. In peritoneal mesothelioma, the asbestos fibers puncture the abdominal lining, which is responsible for secreting lubrication for the organs to process food. When this happens, a cancerous growth forms in the abdominal lining.

The incubation period for mesothelioma can be up to fifty years, with symptoms remaining dormant after exposure to asbestos. By the time symptoms appear, the peritoneal mesothelioma has usually already progressed and spread throughout the body. Adding difficulty in detecting peritoneal mesothelioma is the fact that its symptoms are common and mimic other conditions (some of which are minor conditions), and with such a long incubation period after exposure, a physician may treat a patient for the wrong illness, such as indigestion or heartburn.

Peritoneal Mesothelioma Symptoms

Individuals with malignant peritoneal mesothelioma typically have symptoms such as swelling in the abdominal area, sudden loss of weight and appetite, nausea, constipation, and pain in the abdominal region.

Other common symptoms of peritoneal mesothelioma include abdominal lumps, anemia, blood clots, chest pain, coughing, difficulty breathing, difficulty swallowing, fever, fluid retention in the abdominal cavity, constipation, hernia, nausea, and obstructions of the bowel.

Because these symptoms mimic other conditions and are not specific to peritoneal mesothelioma, sometimes malignant peritoneal mesothelioma is not diagnosed, especially if the patient has no idea or does not recall being exposed to asbestos.

Peritoneal Mesothelioma Diagnosis

When the doctor suspects that a patient may have malignant peritoneal mesothelioma, a magnetic resonance imaging (MRI) or computed tomography (CT) scan will usually be ordered — so they can check for abdominal anomalies. If they do find abdominal anomalies, a biopsy is also ordered to find out what kinds of cells exist within the tissue.

CT scan findings of peritoneal mesothelioma are usually non-specific and insufficient to establish a diagnosis. However, CT scan is useful for detecting, characterizing, staging, and guiding biopsy of peritoneal masses.

Based on CT scan appearances, peritoneal masses are categorized into three types:

• The ‘dry-painful’ type is the most common, in which CT shows a single large mass or multiple small peritoneal masses in one abdominal quadrant, with no signs of ascites.
• The ‘wet’ type is associated with intestinal distension and ascites, widespread small nodules and plaques, and no solid masses.
• Then there is the ‘mixed’ type, which has the characteristics of both the dry and wet types.

A definite diagnosis based on imaging results alone is usually impossible. Additionally, distinguishing a benign mass from a malignant mass, as well as a primary from a metastatic mass is also challenging. Therefore, the definitive diagnosis of peritoneal mesothelioma is dependent on histologic and immune-histochemical examination. Cytologic analysis of ascites (fluid in the abdominal cavity) may also be performed, although it has a low diagnostic potential.

When either imaging scans and cytologic findings are inconclusive (or ascitic fluid is absent), tumor biopsy is performed and this typically results in a conclusive diagnosis.

Peritoneal Mesothelioma Treatment Options

Treatment options for peritoneal mesothelioma are dependent on the extent of which the cancer has progressed. Other factors include the patient’s age, health, and medical history. Typical treatment options include:

• Chemotherapy – The most common treatment for peritoneal mesothelioma, chemotherapy may kill cancerous cells.
• Radiation – Radiation therapy may shrink a peritoneal mesothelioma tumor and kill cancer cells.
• Surgery – Surgery for peritoneal mesothelioma involves removing portions of the abdominal lining, tumor, and possibly parts of the diaphragm.

New treatments for peritoneal mesothelioma include dual therapy, triple therapy, intraoperative photodynamic therapy, immunoaugmentative therapy, gene therapy, and alternative medicine.

Should You Get Tested?

If you have been exposed to asbestos in the past, it is recommend that you get tested immediately for the three types of mesothelioma:

• Peritoneal mesothelioma (cancer of the abdominal lining)
• Pleural mesothelioma (cancer of the lung lining)
• Pericardial mesothelioma (cancer of the heart lining)

Mesothelioma is treatable if detected early enough.