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Peritoneal Mesothelioma

While pleural mesothelioma (mesothelioma of the pleura, the tissue surrounding the lungs) is the most common form of mesothelioma, there are several other forms of this cancer. According to the American Cancer Society, between 10 to 20 percent of mesotheliomas begin in the abdomen; this form of mesothelioma is called peritoneal mesothelioma. A much smaller percentage of mesotheliomas begin in the lining of the cavity surrounding the heart; this form of mesothelioma is called pericardial mesothelioma. Another rare form of mesothelioma attacks the lining surrounding the testicles; it is called mesothelioma of the tunica vaginalis. The lining surrounding the testicles is an extension of the peritoneum (the mesothelium of the abdomen) into the scrotum.

Peritoneal Mesothelioma Symptoms

Relatively little is known about pericardial mesothelioma and mesothelioma of the tunica vaginalis. Doctors have not been able to sufficiently study these forms of mesothelioma because they are so rare. Pericardial mesothelioma may manifest itself with shortness of breath or chest pain. A mass on a testicle may be the first and only visible symptom of mesothelioma of the tunica vaginalis.

Since it is more common, more is known about peritoneal mesothelioma. The American Cancer Society reports that peritoneal mesothelioma may exhibit symptoms such as:

Abdominal swelling
Pain in the abdomen
A change in bowel habits, such as frequent constipation or diarrhea
Unintended weight loss
Lumps of tissue within the abdomen

Unfortunately, the appearance of these symptoms means that the tumor is growing larger. Pressure from the mesothelioma tumor leads to bowel obstruction and swelling of the abdomen as the intestines distend. This can lead to increasing pain, as the growing tumor presses against sensitive nerve fibers. The tumor may also press upward, towards the lungs causing breathing difficulty.

Mesothelioma Imaging & Tests

Imaging tests, including x-rays and CT scans are typically the first tests your doctor will order if you come in with symptoms that may indicate peritoneal mesothelioma. Since the symptoms of peritoneal mesothelioma are similar to other abdominal disorders, a physician will first rule out more common problems before focusing on mesothelioma.

If the imaging tests come back with suspicious indications, a biopsy will be needed. A procedure called peritoneoscopy will be performed to look inside the abdominal cavity. Peritoneoscopy is performed under anesthesia. The doctor will take small tissue samples of any suspicious areas. These samples will be examined under a microscope by a pathologist who will determine if they are cancerous. If they are cancerous, the pathologist will determine whether they are epitheloid, sarcomatoid, or biphasic (mixed); this will help the doctor decide what treatment may be best. These tests will also be used to determine the stage at which the cancer has developed.

Mesothelioma Causes

The primary cause of peritoneal mesothelioma is asbestos exposure. Asbestos is a known carcinogen (cancer causing agent) which has been linked to other forms of cancers in addition to mesothelioma. While it is known how asbestos fibers get into the lungs, the pathway into the peritoneum (the mesothelium of the abdomen) is not clear to scientists. Two theories have been proposed.

Some scientists believe that asbestos fibers may be swallowed during the process of inhaling, because they are caught in the mucus of the trachea and bronchi. These fibers may lodge in the intestines and then move into the peritoneum through the intestinal wall. Other experts theorize that asbestos fibers inhaled into the lungs may move into the lymphatic system and then be moved to the peritoneum.

Scientists do not clearly understand why a carcinogen such as asbestos causes a cell to develop cancerous changes. It is also not known whether a single asbestos fiber can cause a mesothelioma tumor to develop; most people who develop mesothelioma have been exposed to asbestos over an extended period of time.

It is known that people who smoke and have been exposed to asbestos are complicating their risk of developing pleural mesothelioma. Smoking causes cellular changes in the lungs and in other organs, so it may be a risk factor for peritoneal mesothelioma, pericardial mesothelioma, and mesothelioma of the tunica vaginalis as well.

Mesothelioma Treatments

Treatment options for peritoneal mesothelioma, pericardial mesothelioma, and mesothelioma of the tunica vaginalis are the same as those for pleural mesothelioma: surgery, chemotherapy, and radiation. Surgery is an option if at least part of the tumor or tumors can be safely removed. Doctors will evaluate your overall health status before determining if you are a good candidate for surgery.

Chemotherapy refers to any form of drug therapy designed to kill the cancer cells. These drugs may sometimes be given by mouth, but are generally given intravenously (into the veins). Systemic chemotherapy is given by an IV into the arm or hand and allows the drugs to travel throughout the body, targeting cancer cells wherever they are. Unfortunately, this treatment can cause harm to healthy cells as well as cancerous cells.

The aim of chemotherapy is to shrink mesothelioma tumors by killing a least some of their cells. Treating specific areas of the body with chemotherapy can allow doctors to target cancer cells, while lowering the risk to healthy cells. Chemotherapy for peritoneal mesothelioma may be given intravenously directly into the abdomen. This treatment, which is known as intraperitoneal chemotherapy, allows the use of higher doses of drugs and can thus be more effective than systemic chemotherapy. Pleural mesothelioma may be treated with drugs given intravenously into the chest cavity (intrapleural chemotherapy).

Chemotherapy may be given before surgery in an attempt to make the size of tumors more manageable and easier to remove. It may also be given after surgery to target any part of tumors that could not be removed or to reduce the chance that the cancer will return.

Radiation is also used to treat peritoneal mesothelioma. It is not a cure, but may help shrink tumors and reduce the symptoms of abdominal pressure. Radiation therapy can also be used after surgery or a biopsy to prevent cancerous cells from spreading to the incision.

Therapy which uses a combination of surgery, chemotherapy, and radiation is often the most effective, but it is difficult to undergo. Combination therapy is more appropriate for younger mesothelioma patients who are otherwise in good health. Many patients would see no benefit from such aggressive treatment. An open discussion with your doctor will help you determine which treatment options are right for you.

Mesothelioma Prognosis

Pericardial mesothelioma and mesothelioma of the tunica vaginalis can be extremely aggressive and hard to treat. Treatment of peritoneal mesothelioma is somewhat more effective. One of the great obstacles to the treatment of any form of mesothelioma has been that these cancers are hard to detect and are often not diagnosed until they are in the advanced stage and may have spread (metastasized) to other organs.

Currently, numerous clinical trials are underway to study new treatments for all forms of mesothelioma. If your mesothelioma is not responding to conventional treatments, one of these experimental programs may be a good option for you. Make sure to discuss the possible opportunities with your doctor.

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