A layer of specialized cells called mesothelial cells lines the chest cavity, abdominal cavity, and the cavity around your heart. These cells also cover the outer surface of most of your internal organs. The tissue formed by these cells is called mesothelium.

The mesothelium helps protect your organs by producing a special lubricating fluid that allows organs to move around. This fluid makes it easier for the lungs to move inside the chest during breathing. The mesothelium of the chest is called the pleura and the mesothelium of the abdomen is known as the peritoneum. The mesothelium of the “sac-like” space around the heart (pericardial cavity) is called the pericardium.

Tumors of the mesothelium can be non-cancerous (benign) or cancerous (malignant). A malignant tumor of the mesothelium is called a malignant mesothelioma; however, malignant mesothelioma is often simply called mesothelioma.

Malignant mesotheliomas are divided into 3 main types:

• epithelioid (50% to 70% are of this type) — this type has the best outlook for survival (prognosis)
• sarcomatoid (7% to 20% are of this type)
• mixed/biphasic (20% to 35% are of this type)

Treatment options are the same for all 3 types.

About 75% of mesotheliomas start in the chest cavity. They are known as pleural mesotheliomas. Another 10% to 20% begin in the abdomen. These are called peritoneal mesotheliomas. Pericardial mesotheliomas start in the cavity around the heart and are very rare. The covering layer of the testicles is actually an outpouching of peritoneum into the scrotum. Mesotheliomas that affect this covering of the testicles can occur but are quite rare.

It is important not to confuse malignant mesothelioma with benign tumors that also start in the mesothelium. The mesothelium of certain female and male reproductive organs may develop a type of benign tumor called an adenomatoid tumor. In men, this non-cancerous tumor often starts in the epididymis (a small collection of ducts that carry sperm cells out of the testicle). In women, this tumor may begin in the fallopian tubes (tubes that carry eggs from the ovaries to the uterus or womb). Another non-cancerous tumor that may begin in mesothelium near female reproductive organs is called benign cystic mesothelioma.

A type of benign tumor that used to be called benign fibrous mesothelioma can form in the pleura surrounding the lungs. Doctors now know that this tumor actually starts from tissue under the mesothelium and not from mesothelial cells. For this reason, the new name of this tumor is solitary fibrous tumor of the pleura. This disease is usually not cancerous, but cancerous forms can occur. A similar disease starting in the peritoneum is called solitary fibrous tumor of the peritoneum. The tumors described in this paragraph are usually removed by surgery, and there is no need for additional treatment. Only malignant mesothelioma will be discussed further in this document.

Chemotherapy is the use of drugs for treating cancer. The drugs can be swallowed in pill form or they can be injected by needle into a vein or muscle. Chemotherapy is systemic therapy. This means that the drug enters the bloodstream and circulates throughout the body (through the whole system) to reach and destroy the cancer cells.

To treat mesothelioma, these drugs may also be given intrapleurally (directly into the chest cavity) or intraperitoneally (into the abdominal cavity). Based on the type and stage of mesothelioma, chemotherapy may be given as the primary (main) treatment or as an adjuvant treatment (treatment given in addition to the primary treatment) to surgery. Chemotherapy for this disease is palliative and not curative.

Several chemotherapy drugs have been used to treat mesothelioma. The preferred combination of drugs for now is pemetrexed (Alimta), which is combined with cisplatin. Because pemetrexed interferes with normal metabolism of folic acid and vitamin B12, these must also be given to avoid side effects. Another combination that has a good response rate is cisplatin and gemcitabine. Another option substitutes cisplatin with carboplatin, which causes much less nausea and vomiting.

Other combinations of drugs used to treat mesothelioma include:

• methotrexate and vincristine
• cisplatin, vinblastine and mitomycin
• cisplatin and doxorubicin
• doxorubicin, cyclophosphamide (or ifosfamide), and cisplatin

All the drugs above can be given alone in people who may not be able to tolerate two drugs. Other drugs such as paclitaxel and irinotecan are being studied to determine their effectiveness in treating mesothelioma.

A new, related drug called raltitrexed has also been shown to help patients with mesothelioma when given with cisplatin. Patients who received these drugs lived longer than those who received cisplatin alone.

Chemotherapy drugs kill cancer cells but also damage some normal cells. Therefore, your doctor will pay careful attention to avoiding or minimizing side effects, which depend on the specific drugs, the amount taken, and the length of treatment. Temporary side effects might include nausea and vomiting, loss of appetite, loss of hair, and mouth sores.

Because chemotherapy can damage the blood-producing cells of the bone marrow, patients may have low blood cell counts. This can result in an increased risk of infection (due to a shortage of white blood cells); bleeding or bruising after minor cuts or injuries (due to a shortage of blood; platelets); or fatigue or shortness of breath (due to low red blood cell counts).

Most side effects disappear once treatment is stopped. There are remedies for many of the temporary side effects of chemotherapy. For example, you can be given drugs to prevent or reduce nausea and vomiting. If you experience any side effects, be sure to talk with your doctor.

Individuals who have been exposed (or suspect they have been exposed) to asbestos fibers on the job, through the environment, or at home via a family contact should inform their doctor of their exposure history, whether or not they experience any symptoms. The symptoms of asbestos-related diseases may not become apparent for many decades after exposure. It is particularly important to check with a doctor if any of the following symptoms develop :

* Shortness of breath, wheezing, or hoarseness.
* A persistent cough that gets worse over time.
* Blood in the sputum (fluid) coughed up from the lungs.
* Pain or tightening in the chest.
* Difficulty swallowing.
* Swelling of the neck or face.
* Loss of appetite.
* Weight loss.
* Fatigue or anemia.

A thorough physical examination, including a chest x-ray and lung function tests, may be recommended. The chest x–ray is currently the most common tool used to detect asbestos-related diseases. However, it is important to note that chest x-rays cannot detect asbestos fibers in the lungs, but they can help identify any early signs of lung disease resulting from asbestos exposure .

Studies have shown that computed tomography (CT) (a series of detailed pictures of areas inside the body taken from different angles; the pictures are created by a computer linked to an x-ray machine) may be more effective than conventional chest x-rays at detecting asbestos-related lung abnormalities in individuals who have been exposed to asbestos .

A lung biopsy, which detects microscopic asbestos fibers in pieces of lung tissue removed by surgery, is the most reliable test to confirm the presence of asbestos-related abnormalities. A bronchoscopy is a less invasive test than a biopsy and detects asbestos fibers in material that is rinsed out of the lungs. It is important to note that these tests cannot determine how much asbestos an individual may have been exposed to or whether disease will develop . Asbestos fibers can also be detected in urine, mucus, or feces, but these tests are not reliable for determining how much asbestos may be in an individual’s lungs .