There are three forms of mesothelioma. All forms are the result of exposure to asbestos. Pleural mesothelioma is the most common form. It affects the lungs, the protective lining and cavity of the lungs. The patient may experience shortness of breath, chest pains, and a persistent cough. All these symptoms are caused by pleural effusion; this is a fluid build up in between the lining of the lung and the chest cavity.
Peritoneal mesothelioma is a rarer form that starts in the abdomen and can spread to other areas of the body. The patient’s symptoms are abdominal pain, nausea, vomiting swelling and loss of appetite.
Pericardial mesothelioma is the rarest form of this disease. It starts in the cavity surrounding the heart and the tumors can spread to other areas of the body. Patients with this form of mesothelioma may experience, chest pain, shortness of breath and palpitations.
Asbestos is a soft and flexible mineral that has been in use for many centuries. The Ancient Greeks gave it the name asbestos because of its amazing fireproof qualities. Asbestos literally means inextinguishable. It was during industrial revolution that asbestos became popular and was used in structures such as ceilings and walls to provide insulation.
It was in the 1900’s that the risks to asbestos workers began to emerge. It was in the mid 1920’s that an English doctor made the first diagnosis of asbestosis. Asbestos continued to be used until the mid-seventies and unfortunately many workers had already been exposed to asbestos fibers and contracted mesothelioma. Today, there are many laws and regulations in place to prevent workers being exposes to asbestos, thus preventing workers from contracting this form of cancer.
Mesothelioma is a cancerous disease that affects the mesothelial cells that make up the mesothelium. This is the outer lining that protects the major organs such as the heart, stomach and the lungs. This type of cancer is a direct result of continuous unprotected exposure to asbestos. Persons who are the most at risk for developing mesothelioma are those who have worked with asbestos for many years. The organs most affected by mesothelioma are the lungs, heart and abdomen. The lungs which is known as pleural mesothelioma, the heart which is know as pericardial mesothelioma and finally, the abdomen, know as peritoneal mesothelioma. The symptoms of mesothelioma are very common and can mimic many other well known diseases. Therefore, it is not unusual for the patient to be misdiagnosed. It is very important that the patient is diagnosed early so treatments can begin, which increases the survival rate.
Surgery, Radiation and Chemotherapy. The decision on which one or combination relies on a number of factors including: location of mesothelioma, spread and staging, and age and health of patient. Surgical options include removal of affected area (pleurectomy), organ (pneumonectomy), or fluid (thoracentesis and paracentesis). Radiation attacks and kills the cancer cells, this can be done with internal or external radiation methods. Chemotherapy uses a combination of medications (oral, injectable, intravenous and topical) to attack the mesothelioma. Since all treatment options a currently palliative, goals should include pain management, restoring/maintaing lung function and quality of life. Clinical trials using a number of approaches and combinations of the above are also viable options.
First, a high-index of suspicion is necessary after taking a thorough history of the patient, their symptoms and past exposures. Secondly, a chest x-ray will likely display pleural effusion and/or generalized thickening of the pleural tissue. Chest x-ray abnormalities should prompt further imaging studies including CT scan or MRI of the chest. These will then display the possiblility of mesothelioma as a diagnosis. At this juncture, a bronchoscopy may be an option. However, the definitive diagnosis can only be made with an actual tissue sample via biopsy. This is often done through a thoracoscope. Other methods of tissue biopsy include open biopsy and needle biopsy. Tissue biopsy is superior to fluid sampling.
Likely the greatest challenge is the long latency period, from time of exposure to start of symptoms. Symptoms may develop anywhere from 20 to 50 years after exposure. Another challenge is the fact that even small or indirect exposures to asbestos can cause a mesothelioma and an individual may not report a history of exposure. An example of this may be a man that works around asbestos and his wife that shakes the dust off of his clothing before laundering. The wife may not report asbestos exposure. Further making the diagnosis difficult is the presenting symptoms are often much like the symptom of multiple other illnesses. For example, some symptoms of pleural mesothelioma may be shortness of breath, chest pain, coughing and hoarsness. These symptoms may also be present with bronchitis, myocardial infarction, laryngitis, pneumonia and a number of other common conditions.
There are three types. Mesothelioma is a tumor of the mesothelial cells which make up the lining that surrounds and protects the heart (pericardium), lungs (pleural) and abdomen (peritoneal). Pleural mesothelioma is the most common and affects the lungs. Pleural mesotheliomas can be benign or malignant,with the cancerous type being most common. Prognosis is poor with approximately a 17-month survival from symptom onset. Peritoneal mesothelioma affects the abdomen and is the second most common of the mesotheliomas. Prognosis for peritoneal mesothelioma is worse at 10 months from symptom onset. There is a rare and benign form of peritoneal mesothelioma, seen mostly in young females. Pericardial mesothelioma affects the heart, this is the rarest of the three and prognosis is the poorest.
Mesothelioma is a tumor that can be benign or malignant. Those at highest risk for developing mesothelioma are those that have been exposed to asbestos. Exposure does not have to be significant. Occupations that put people at risk for asbestos exposure include, but are not limited to: miners, shipyard workers, insulators, factory workers, railroad workers and manufacturers of gas masks. Family members of those working around asbestos are also at risk for developing mesothelioma, as they exposure to asbestos as well. Asbestos particles often remain on the body and clothing of the exposed worker, therefore those family members around the worker can ingest the asbestos dust and become exposed. Those involved in laundering clothes of the asbestos-exposed worker, also become at risk for developing mesothelioma. Tobacco is not an independent risk factor for developing mesothelioma; however, tobacco plus asbestos exposure significantly increases ones risk for developing mesothelioma.
Treatment of mesothelioma includes surgery, chemotherapy, radiation, and a combination of the three, termed trimodality therapy. Surgical intervention can be diagnostic and palliative but rarely curative. Surgical procedures include pleurodesis, pleurectomy, and extrapleural pneumonectomy. Radiation therapy is difficult in mesothelioma because of the sensitivity of local organs to radiation, but can still provide local palliation in almost 50 percent of patients. Chemotherapy is rarely used alone but is an important part of trimodality therapy, which has produced the most favorable results. This approach combines the use of surgery, typically extrapleural pneumonectomy, with chemotherapy and postoperative radiation. Patients must undergo extensive evaluation before this treatment option is considered, including chest MRI, echocardiography and full pulmonary function testing. Patients older than 55 years may not be candidates because of increased perioperative mortality. New therapeutic approaches include intracavitary therapy, where compounds are delivered directly into the pleural space, and gene therapy.
The choice of radiographic studies and laparascopic investigation to accurately determine extent of disease is under debate. Both gadolinium contrast MRI scans and PET scans have been shown to aid in staging of mesothelioma. Others, however, argue that laparoscopic thorascopy is the most appropriate tool for assisting in staging. Current TNM classification is as follows:
Stage I: Completely resected within capsule of parietal pleura without adenopathy
Stage II: All stage I characteristics with positive resection margins, adenopathy, or both
Stage III: Local extension of disease into chest wall, mediastinum, diaphragm, peritoneum, or to extrapleural lymph nodes
Stage IV: Distant metastatic disease
Prognosis of mesothelioma is extremely poor. Without any treatment, mesothelioma is typically fatal within 4 to 13 months of diagnosis. Regardless of therapeutic approach, treated patients can expect a 6 to 18 month median survival rate. Few patients have survived 5 years after diagnosis.