Mesothelioma is a disease characterized by unilateral, non pleuritic chest pain and dyspnea. It is a type of cancer usually caused by exposure to asbestos (an element). Common site for its appearance are pleura but it may also appear in peritoneum or pericardium.
Mesothelium is a protective lining that covers most of the body parts. Deposition of asbestos fibres in the lung parenchyma due to inhalation can lead to this fatal condition. These asbestos fibres are of two types mainly:
The blue asbestos fibres are long thin fibres where as white asbestos fibres are feathery fibres. Of these the blue asbestos fibres are the most likely ones to lead to this condition. These long thin fibre traverse the lung parenchyma , making their way through visceral peritoneum into the pleural cavity. Once in the pleural cavity it comes in contact with the mesothelium and leads to development of cancer on account of its carcinogenic action.
There is still a lot of research going on about the exact mechanism lying behind the carcinogenic action of asbestos as well as regarding the pathology involved in the manifestation of this disease. So far what believed is that the asbestos fibres come in contact with the mesothelium and cause formation of lesions. Phagocytic cells and macrophages travel to the site of lesion as a response by bodies defense mechanism what we call as immune system.
This lesions continue to attract numerous macrophages and phagocytic cells , as this feed forward type of a response by body continues and macrophages and phagocytic cells keep accumulating in the region. Eventually certain morphologic changes occurring within the lesion lead to the formation of a malignant tumour. We can say that asbestos fibres make their impact by coming in direct contact with cells of mesothelium and indirectly through their interaction with pahgocytic cells and macrophages.
The asbestos fibres also find their way into the chromosomal structure of the related cells. These long fibre move into the nucleus and get entangled into the chromatin material and can lead to widespread changes in the chromosomal structure , most common of which is Monosomy 22. How asbestos fibres find their way to the pleura is easily understandable but the mechanism underlying the spread of asbestos fibres to periotoneum is still under debate . what most scientist agree upon is that these fibres reach peritoneum through the lymphatics.
Unfortunately, Mesothelioma takes quite a bit of time to manifest itself. Its symptoms occur at about 20 to 50 years after exposure to asbestos. Therefore, the disease builds up gradually. Pleural mesothelioma shows up with symptoms including shortness of breath, cough and pain in the chest. They are all attributed due to accumulation of fluid abnormally in pleural cavity. Patient's voice becomes hoarse and thick.
Plus, he is often fatigued and his blood picture shows anaemia. In certain cases masses of tumors are formed which can cause penumothorax and may cause the lungs to collapse. Appearance of blood in sputum is a common finding. Peritoneal mesothelioma manifests itself with symptoms related to those of cachexia (muscle atrophy, weakness,loss of weight, fatigue, loss of appetite). Other symptoms usually include bowel obstruction, blood clotting abnormalities, anaemia and fever.
If the cancer spreads to other parts of the body additional symptoms may occur. They can include pain, difficulty in swallowing and swelling of neck. The face may be observed. Tumors of the abdomen usually do not show any symptoms until very late in the disease. This can be detrimental for the patients.
Moreover, In severe cases of disease additional symptoms like blood clotting in veins, disseminated intravascular coagulation , jaundice , low blood sugar level , pleural effusion and ascites may be seen. An important point is that Mesothelioma does not spread to bones, adrenal glands or brain usually. In the case of pleural tumors, they are found unilaterally in the lungs.
Diagnosis of mesthelioma is a complicated phase of this disease because the symptoms of this disease can be misleading and may lead to errors in diagnosis. The diagnosis can proceed by first of all taking a history of the patient and keeping in view his working environment and his living conditions.
As we know that the prevalence of this disease is greater in the mine workers , people in construction or living near demolished areas as asbestos is present in the air in those areas. Hence knowing the condition through which patients have come through can be a good hand in diagnosis. A physical examination is done after taking the history of the patient. This ohysical examination is followed by chest x-ray. In chest x-ray one tries to look for pleaural thickening which will indicate mesothelioma.
Apart from chest x-ray we also perform lung function test. Lung function give us a clear picture of the status of the patients lungs and their condition. A CT scan and an MRI may also be performed. If a large amount of fluid is present then that fluid can be obtained through pleural tap and examined for abnormal cells and cytological studies. It is to be noted that absence of malignant cells does not rule out mesthilioma at all.
However if cytology shows us signs of malignant cells than they move a step ahead and go for biopsy of the tissue from area which seems abnormal. In the case of chest being the area thoracoscopy is performed where as in case of abdomen laproscopy is performed. After confirming mesthilioma it can be staged as ; if the cancer is preent only in the membrane and has not metastasized it is referred as localized and if the cancer has spread to deep layers and surrounding tissues then it is referred as advanced.
Unfortunately the treatment techniques so far applied for this disease are not effective and patients do not survive to live for more than a year. There are certain factors involved in this disease which make it difficult to be treated.
They can be stated as:
Surgery has been applied to remove lung pleural membranes from the region.Unfortunately, it has not been useful to increase the survival rate. What makes it more aggravated is the fact that the whole mesothelium can not be removed without killing the patient. Radiation involving techniques have been used in the patients who can with stand radiotherapy.
It has been used to treat the localized malignancies. It has come up with great results and the patients have seen to go on and live 5 years and sometimes even more. Chemotherapy has also been employed as a treatment for this disease. It was first officially used in 2004. Therefore, one can not say much about its effectiveness as the research is being carrying out on it. Immunotherapy is another line of treatment.
It has yield variable results and in certain cases reducing the malignant mass to 50 % of it. Encouragingly, it had no side effects. For this therapy interleukin 2 was found to be the main force . Recently a technique known as " heated intraoperative intraperitoneal chemotherapy " was employed for the treatment . It involved infusion of heated chemotherapeutic agents and it has been successful in destroying the malignant cells to a great extend.
Mesothilioma is yet to be studied comprehensively by the researchers. According to some doctors, in the years to come there will be an out break of cases in people suffering from world trade centre syndrome. The collapse of the twin towers released a huge amount of asbestos which was in the air for many weeks and which spread around to the areas and unfortunately it may have found its way to the lungs of many people.
The asbestos workers are quite susceptible to mesothilioma. Therefore, many legal lawsuits have been filed by workers against asbestos manufactures. The first lawsuit was in 1929 and after that many has been filed and the compensation money is said to be around billions of dollars according to some sources. However, sometimes the figures are just exaggerated and the workers do not get enough compensation.
At government level, for the past decade it has been emphasized upon to reduce the use of asbestos in materials where it has a replacement. Although, it was used as a fire retardant and insulator once but after the increase in the complaints, this practice was discontinued. This was an effort to remove asbestos from building materials and other blocks in order to prevent public from coming in direct contact to it.
The government is trying to play a bilateral role. It is not only increasing the amount of protection given to the workers but also increasing the amount of compensation given to the companies. While government provides the companies support and help them to reintegrate their prevailing systems that leads to mesothelioma.