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Malignant Mesothelioma originates from serosal cells of the pleural, peritoneal, and pericardial cavities and from the tunica vaginalis testis. Malignant pleural mesothelioma is an aggressive tumor of the pleura. Symptoms are dyspnea and chest pain in majority of patients. Coughing, fatigue, and weight loss are also reported.
Despite many years of clinical research, there is still no effective therapy for this disease.
Two layers of mesothelial cells called parietal and visceral pleura cover the lung. In between the pleura these is a pleural cavity, which is moistened by a fluid called pleural fluid. The main function of pleura is protection. It helps to create a negative pressure in chest cavity, which is essential for the process of respiration. The movement of lungs during respiration is made frictionless by the presence of pleura and pleural fluid.
Mesothelioma may also affect the peritoneum, which is a mesothelial tissue in the abdomen. The peritoneum covers the abdominal organs. It is also having two layers. The outer parietal peritoneum is attached to the inner wall of the abdomen. Inner visceral peritoneum is attached to the abdominal organs. In between the two layers there is a cavity called peritoneal cavity. Very rarely mesothelioma affects the pericardium. It is the covering seen around the heart. It is also having two layers, fibrous pericardium and serous pericardium.
There are three main types of malignant mesothelioma.
1) Epitheloid: Affects the covering surrounding the internal organs and internal surface of the body. 70% of all cases of mesothelioma are epitheloid.
2) Sarcomatoid: This type affects bones, muscles, and cartilages. 5 to 20 % of cases are of this type. It is more serious than epitheloid type.
3) Mixed type: This type contains both sarcomatoid and epitheloid varieties. 20 to 35% are of this type.
Regardless of the area it affects mesothelioma is fatal. The tumor cells may spread to heart and abdominal organs.
Signs and symptoms:
Men are more affected. Age is usually over 40. The symptoms of mesothelioma are some times confused with that of common cold or allergic lung disorders. The signs and symptoms may vary according to the parts affected.
Initially the patient may complain about constant chest pain. Gradually he will develop breathlessness with cough. The chronic cough worsens over time. Recurrent lung infection is seen in some patients. Patient may complain about shortness of breath with bloody expectoration.
Diagnosis:-
Even with best techniques mesothelioma often evades diagnosis. Early and constant screenings are paramount for those who have suffered asbestos exposure.
The diagnosis is not so easy because;
1) First of all there are few outward symptoms until the condition is gravely advanced.
2) The time between exposure and clinical manifestation takes decades.
3) Mesthelioma often continues even after the exposure has ended.
4) Many sumptoms are common to other less serious diseases.
Treatment:-
The line of treatment is based upon the stage of cancer, location of the tumor and the general condition of the patient.
The usual treatment plans are radiation surgery and chemotherapy. New treatments like photodynamic therapy, angiogenesis therapy and gene therapy etc provide new hope for mesothelioma patients.
Nowadays multimodal therapy is also done to extend the life of affected patient.
Chemotherapy:
Mesothelioma does not respond well to the chemotherapy due to the presence of layers of dead cells around the tumor. Hence the medicine will not reach the cancer cells. Anti cancerous drugs are given in the form of pills or intravenous injections or directly into the affected site. These drugs can kill the cancer cells to some extent. The drugs can also produce some side effects like hair loss, nausea, diarrhoea, anemia, haemorrhages and some toxic reactions. Chemotherapy can suppress the immune system, which will create a chance for infections.
Surgery:
The aim of surgery is to give some relief to the patient. By the removal of tumor, pressure effects on other organs can be removed.
a) Pleurectomy: Here the affected part is removed.
b) Pneumonectomy: Affected lung is removed.
c) Thoracenteses and Paracentesis: The procedures are required to remove the fluid collection.
d) Extra pleural pneumonectomy: This method can potentially extend life for a few more years but is not a cure.
Radiotherapy: Radiation can shrink the tumor to a manageable size. It can also give relief to pain. Radiation is usually combined with chemotherapy and surgery. Radiation wires, tubes, catheters and needles are used nowadays. Radiation can kill the healthy cells near the tumor, which is a drawback.
Multimodel therapy: It is the combination of radiotherapy, chemotherapy and surgery.
Photodynamic therapy: It is one of the modern methods of treatment. Here a special drug is introduced into the tumor cells. When a laser or high intensity light is shined on it the drug will become active and will kill the cancer cells. This method is also having some limitations. The laser can't penetrate deep in to the body. This method can also kill the healthy cells in which the special drug is absorbed.
Immunotherapy: Immunotherapy concentrates on boosting the immune system to fight against cancer cells. By stimulating the immune system the spread of cells can be prevented.
Angiogenesis therapy: Cancer cells need more blood supply than other normal cells. For this purpose number of capillaries is formal around a tumor. This pathological process is called angiogeness. The angiogenesis promoters secreted by the tumor cell indicate this. By introducing an angiogenesis inhibiting factor angiogenesis can be prevented. When the blood supply to the tumor reduces naturally the tumor size and growth will reduce. This method is in the initial stage of trial and is a new hope for cancer patients.
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