There are three cellular classifications for mesothelioma: epithelioid, sarcomatoid, and biphasic. By far the most common cellular base for mesothelioma is the epithelioid cell, which under normal circumstances is the cell that forms tissues and membranes. Epithelial cells cover both the outer and inner surfaces of the skin. They make up membranes such as the mesothelium, the layer of tissue from which the name ‘mesothelioma’ is drawn. Mesothelioma develops in this tissue where it lines the chest wall, lines the outer surface of the lungs, lines the abdominal wall, and forms a sac around the heart.
Both sarcomatoid and epithelioid cells are found in biphasic mesothelioma, requiring a treatment protocol that attacks the weaknesses in both types of cells. About 20% of all mesothelioma diagnoses are for the biphasic type. Perhaps 10% of all cases have malignant sarcomatoid cells.
Sarcomatoid Cell Features
The sarcomatoid cell is also called a spindle cell because of its elongated shape featuring a long, thin nucleus. They develop from the cells of connective tissue unlike the epithelioid cell. Sarcomatoid cells are noted for their aggressive behavior; sarcomatoid mesothelioma will spread more rapidly than the epithelioid form of the disease. Sarcomatoid cells are also always associated with a tumor of some sort, making a correct diagnosis of mesothelioma somewhat difficult. Sarcomatoid cancers can develop in the kidneys, in muscle tissue, in fibrous tissue and in fat tissue. A sarcomatoid form of mesothelioma may be mistaken for pleural plaques because of fibrous nature of plaques located in the visceral pleura or the parietal pleura (the chest wall).
Treating Sarcomatoid Mesothelioma
There are established chemotherapy drugs used for epithelioid mesothelioma: cisplatin, pemetrexed, gemcitabine, and oncanase. Sarcomatoid cells show a limited response to these drugs. Some of the more recent treatment regimens have extracted better response but sarcomatoid mesothelioma remains a lethal, incurable disease. Intrapleural or intraperitoneal chemotherapy applies the drugs directly to the afflicted area rather than using the systemic approach of infusion. Direct application of chemotherapy drugs using a surgically installed tube can have an elevated effect; it has proven to be an effective method of treatment in several cases of peritoneal mesothelioma. The issue with sarcomatoid mesothelioma remains identifying the mixture of chemotherapy drugs that will have an impact on sarcomatoid malignancy.
External radiation is also employed with this cell type, again with limited results. There is some indication that targeted, high intensity radiation can have an amplified effect but that may require radiation treatment during the course of treatment. The use of linear accelerator radiation treatment machines has provided some of the precision targeting capabilities needed for this type of treatment for sarcomatoid mesothelioma.
Sarcomatoid Mesothelioma Prognosis
The survival rates for sarcomatoid mesothelioma are not promising. The disease moves more rapidly than epithelioid mesothelioma and is less responsive to the current chemotherapy drugs employed for malignant mesothelioma treatment. The mean survival time after diagnosis for sarcomatoid mesothelioma patients is less than ten months. For cases of biphasic mesothelioma where both types of cells are present the treatment options become somewhat complicated as the physician tries to develop effective techniques for treating both cell types.
Legal Rights for Sarcomatoid Mesothelioma Patients
The only known cause for mesothelioma is exposure to asbestos. Hundreds of thousands of lawsuits have been filed against asbestos product manufacturers, resulting in billions of dollars in paid claims.
High Dose Radiotherapy for Malignant Mesothelioma, Journal of Medical Imaging & Radiation Oncology, Feigen et al, June 2011
Treatment of Sarcomatoid Carcinoma…American Society of Clinical Oncology, Staddon et al, 2008