Mesothelioma

There are two types of cells associated with malignant mesothelioma: epithelioid and sarcomatoid. Mesothelioma develops from one of these two types of cells, or develops as biphasic mesothelioma which is a combination of the two. Epithelial mesothelioma defined by its malignant epithelioid cells, occurs in up to sixty percent of all cases of the disease. Sarcomatoid is relatively rare, occurring in less than ten percent of all cases. Epithelial is by far the most common cellular form of mesothelioma.

The epithelial cancer cells that develop with mesothelioma are the most responsive to the treatments currently available for mesothelioma. Patients with this form of the disease have longer average survival times than those who develop biphasic mesothelioma or those who have sarcomatoid cells associated with their cancer; these are more resistant to treatment than epithelial cells and faster growing.

Epithelial cells are common to connective tissue, such as is found in the inner surface of the lungs as well as in the mesothelium. It is a common type of cell and in its malignant form can be quite similar in the case of mesothelioma and adenocarcinoma, which can be a type of lung tumor. The confusion over these similar epithelial cells can often lead to misdiagnosis.

Epithelial malignant mesothelioma can affect different areas of the body. Mesothelioma is cancer to any of the tissues that surround internal organs. Sixty percent of epithelial malignant mesothelioma occurs in the pleural tissues of the lungs. This develops almost exclusively as a result of asbestos inhalation. The symptoms of epithelial malignant mesothelioma that affect the lungs include:

Many patients are asymptomatic. The right lung is affected sixty percent of the time, the left lung thirty five percent, and both lungs are affected in five percent of epithelial malignant mesothelioma cases.

Epithelial malignant mesothelioma is also common in the peritoneum of the abdomen. This is caused by the ingestion of asbestos that enters the air. Patients with this type of mesothelioma may also remain asymptomatic for years and years, though the following symptoms may be present: weight loss, nausea, effusion (fluid build-up) in the stomach, bowel difficulties, foot swelling and anemia. Malignant mesothelioma can also affect the reproductive organs, the heart, and other major organs.

A person who has been exposed to asbestos for one or two months has the potential to develop epithelial malignant mesothelioma or other asbestos related illnesses up to fifty years later. Mesothelioma has a long latency period. Once diagnosed the prognosis is often bleak. The average patient has a year left to live after they discover their condition.

People who are at risk for developing epithelial malignant mesothelioma include employees who work with asbestos containing materials. Construction workers are particularly at risk, though professionals in the building, shipyard, railroad, and automobile industries as well as people with custodial duties may also be at risk. People who were exposed to asbestos as long ago at the 1940s may still be at risk for contracting this life threatening cancer.

For years mesothelioma treatment has consisted of a combination of surgery and chemotherapy, and often radiotherapy as well, with limited results. The average survival time after diagnosis for this disease hasn't moved much beyond one year. Today however there are some surgeons getting impressive results with cases that have the epithelial characteristic. The technique includes aggressive surgery for both pleural and peritoneal mesothelioma. In the case of pleural mesothelioma, the malignancy of the lung lining and the most common form of the disease, the surgeon has a few choices. The most common are the pleurectomy, which is resection of the pleura – the membrane that encases the lungs and on which the mesothelioma tumors form.

The most aggressive approach is the extrapleural pneumonectomy, which involves removing the pleural membrane and the lung on the affected side of the body. Many surgeons feel that epithelial mesothelioma is the only type that is appropriate for this approach because the epithelial cells will respond to chemotherapy whereas the sarcomatoid cells are more difficult to impact. One study of 120 such procedures revealed a survival rate of 65% at two years for epithelial mesothelioma and 20% at two years for sarcomatoid or biphasic patients.

In addition to aggressive surgery the newer therapy regimens utilize hyperthermic intrapleural or intraperitoneal chemotherapy, which involves putting chemotherapy medication directly on the tissue to be impacted during surgery and by using a shunt or tube during postoperative therapy. This approach generally utilizes pemetrexed and cisplatin, two medications that have proven to work with epithelial cells. Directed radiotherapy and occasionally photodynamic therapy is also applied in these cases, and the results – with epithelial mesothelioma – have been impressive.