Epithelioid mesothelioma is the most common type of the disease, accounting for 60 to 75 percent of all new cases. It will generally begin to show visible symptoms between ages 50 and 70, with upwards of 80 percent of new diagnoses being in men. Cancers of epithelial tissue are called carcinomas. A study published in the September 2000 respiratory medicine journal Thorax determined that epithelioid mesothelioma patients had a better prognosis than those diagnosed with sarcomatous or biphasic mesothelioma.
The entire human body and all of its internal and external organs are covered with epithelial tissue. These protective tissue clusters are packed very close together, with little to no space between cells. Epithelial tissue is what makes human skin waterproof. There are eight types of epithelial tissues, including transitional cells that line the bladder, simple cuboidal cells found in the kidneys, and stratified squamous cells that line the skin, throat and esophagus. Epithelial tissue is different from connective, muscle and nervous tissue because each cell is polarized, attached to one another, and is attached by a basement membrane to underlying tissue. Pleural malignant mesothelioma is by far the most common epithelioid-related diagnosis. It comprises 75 percent of all mesothelioma cases, according to the American Cancer Society. Occupational exposure to asbestos is directly related to more than 90 percent of these cases. Asbestos is inhaled and the sharp fibers literally dig into the epithelial tissue lining the lungs. The inflammation caused by the asbestos fibers leads to malignancy.
The latency period can range anywhere from 15 to 60 years. This is why mesothelioma mostly affects older people. Those diagnosed with mesothelioma in the age 30 to 40 range were usually exposed to asbestos as children in some way. An epithelioid mesothelioma diagnosis is difficult for doctors simply because many of the symptoms resemble common ailments. Chest pain, shortness of breath, unexplained weight loss, and a chronic cough. Doctors will first determine any history of asbestos exposure with the patient. It then comes down to diagnosing the type of mesothelioma, then the affected cell type (i.e. epithelioid). A computerized tomography (CT) scan is useful for pinpointing, among other things, nodular pleural thickening and mediastinal pleural involvement. These are sure signs of pleural mesothelioma. Immunohistochemistry, a procedure used to differentiate between malignant mesothelioma and other cancers, may also be used for determine a positive diagnosis. Needle and cytology biopsies are sometimes used, but can be ineffective due to the small sample sizes derived thereof.
Prognosis and Treatment
The treatments available and prognosis for epithelioid mesothelioma depends entirely on the stage and location. A 1994 study published in the European Respiratory Journal found that stage 1 patients lived for 359 days after diagnosis. Stage 3 and 4 patients lived for 112 days on average. A 2011 University of South Wales (Australia) study found that estrogen receptors in women may suppress the development of tumors, giving females a longer prognosis than men. Younger patients also tend to live longer due to more treatment options being available to them. Epithelioid mesothelioma accounts for a vast majority of diagnosis, thus there are more treatments available and a longer prognosis. Some combination of surgery, radiation, and chemotherapy (also called multimodal therapies) is normally the course of action to attack the cancer. A multimodal treatment may include an extrapleural pneumonectomy (surgical removal of the affected lung, along with parts of the chest and heart lining), then localized radiation to reduce the risk of recurrence. The current relative five-year survival rate for mesothelioma patients is nearly 10 percent, which is significantly higher than the rate in the 1980s. Anyone who believes they were exposed to asbestos at any point in their lives to see a doctor even if symptoms seem minor. The sooner the diagnosis, the longer the prognosis.