Epithelial mesothelioma is a rare cancer that is caused by exposure to asbestos. Asbestos is a mineral fiber frequently used in materials such as insulation in construction due to its strength and heat-resistance. However, when the materials that contain asbestos are damaged and the dust is inhaled, serious and life-threatening health effects result. Epithelial mesothelioma is the most common type of asbestos-caused cancer and has a slightly better outlook than the other two types—sarcomatoid and biphasic/mixed. However, the average life expectancy following diagnosis of this type of cancer is still up to 1 year.
The epithelial tissue is the membrane surrounding internal organs, and it provides coverage to all body parts. Symptoms of epithelial mesothelioma are vague and depend on which organs and area of the body are affected. The cancer cells can form in the heart, known as pericardial mesothelioma; in the tissue of the lungs, called pleural mesothelioma; or in the abdomen, referred to as peritoneal or abdominal mesothelioma. Also, in rare cases, tumors can form in the testicles, called testicular mesothelioma.
Symptoms of Epithelial Mesothelioma
Depending on which area of the body is being affected, symptoms are varied and can range from shortness of breath and chest pain to weight loss and abdominal swelling. Given that symptoms can be mild and indistinguishable from other common illnesses, a diagnosis is often not made until the cancer has reached the later stages, when it is less treatable.
Aggressive treatment such as surgery and radiation can be much more effective in the earlier stages, and studies have demonstrated a 50% survival rate of up to 5 years when treatment began during Stage 1. As early detection is vital to a better prognosis, if an individual is experiencing symptoms indicative of epithelial mesothelioma and has had known exposure to asbestos dust, further diagnostic tests are warranted.
Diagnosing Epithelial Mesothelioma
Diagnosing epithelial mesothelioma is a tough task. The cancer may often be confused with adenocarcinoma, another epithelial cancer that has characteristics similar to one of the subtypes of mesothelioma, glandular mesothelioma.
Radiology and pathology exams, as well as a discussion about previous asbestos exposure, will be used to diagnose the cancer. Patients may also be screened using immunohistochemistry or other immunological techniques to study the makeup of the tissues.
Cytology and needle biopsies are also utilized in helping to determine whether an individual has epithelial mesothelioma; however, they are often ineffective because a larger sample of the affected tissue is needed to determine the subtype of mesothelioma. Other medical procedures such as an internal exams or biopsies of the pleural cavity, also known as thoracoscopy, may aid in distinguishing between epithelial mesothelioma and adenocarcinoma.
The most effective type of treatment for fighting and preventing the spread of cancer cells will depend on the severity of the cancer and where it is located in the body. Chemotherapy alone has not been shown to be an effective treatment but can be used in conjunction with radiation or surgery. Chemotherapy and radiation function to reduce the presence of cancer cells but also damage healthy cells, resulting in numerous side effects.
Surgery can help to alleviate the pain patients in later stages of the cancer are experiencing. In addition, surgery can attempt to cure individuals of cancer or better their prognosis for longevity. It is extremely important to discuss the benefits and risks of all treatment options with the doctors who are treating the disease to make informed decisions.
Subtypes of Epithelial Mesothelioma
Characterized by their shape, size, and structure, subtypes of epithelial mesothelioma include the following:
- Adenoid cystic
- Signet Ring
- Single File
- Small Cell
- Poorly Differentiated (large cell) or Pleomorphic
- Mucin Positive
- Gaucher Cell-Like
- In Situ
- Well-Differentiated Papillary
A common subtype of epithelial mesothelioma is deciduoid mesothelioma. Originally, cases involving four young women without exposure to asbestos were reported. All four of these cases involved the peritoneum, and it was suggested that this subtype, given its unique morphology, is unrelated etiologically to asbestos.
However, according to a study published by Pub Med from the University of Texas, four cases of three men and one woman, ranging in age from 46 to 78, were reported to have deciduoid features present in their mesothelioma. Two of the four patients had previous exposure to asbestos. These findings indicate that this variant of epithelial mesothelioma is not limited to a specific patient population or restricted to the peritoneum.