The condition is slow to develop. The â€ślatency periodâ€ť between first exposure to asbestos and the development of clinically obvious mesothelioma is usually 20-35 years but can be as long as 50 years and as short as 10 years. Mesotheliomas have usually been growing for 10-12 years before becoming clinically obvious.
The most common form of mesothelioma attacks the pleura (â€śpleural mesotheliomaâ€ť).
Pleural mesothelioma can be either:
- (1) diffuse and malignant (cancerous), or
- (2) localised and benign (non-cancerous.)
Benign mesotheliomas can often be removed surgically, are generally not life-threatening, and are not usually related to asbestos exposure.
Malignant mesotheliomas, however, are very serious and almost always result from exposure to airborne asbestos fibres. The details below apply to malignant mesothelioma.
Pleural Mesothelioma â€“ Symptoms
Symptoms may include shortness of breath, chest pains, lower back pains, persistent coughing, weakness, weight loss, loss of appetite or difficulty in swallowing. At first a person with mesothelioma may be breathless only during heavy exertion, but as lung function drops, sufferers can become short of breath even while resting. The mesothelima may also be accompanied by pleural thickening and/orÂ pleural effusions.
As the disease progresses the tumour spreads by direct invasion of surrounding tissue. Inward growth of the tumour can compress the lungs. As the tumour spreads outward it can invade the chest wall and ribs, and this can be extremely painful.
Pleural Mesothelioma â€“ Diagnosis/Treatment
Detection is usually by chest x-ray or CT scan followed by a â€śbronchoscopyâ€ť when a viewing scope is used to look inside the lungs. Diagnosis of the condition is then confirmed by taking a small sample of tissue by a surgical procedure called a â€śbiopsyâ€ť.
The biopsy can either be a â€śneedle biopsyâ€ť, an â€śopen biopsyâ€ť, or a â€śthoracoscopyâ€ť, or chest scope, whereby a tube with a camera is inserted into the lungs. In a thoracosopy a tissue sample can be taken from any abnormality seen through the camera using the same tube. This is a simple hospital procedure that does require anaesthesia, but is not usually painful. The sample tissue is then tested sent for pathological testing. This is important because there are also benign tumours that have a similar appearance to mesothelioma.
As yet there is no known cure for malignant mesothelioma. However clinical trials are being undertaken for various new treatments and combinations of treatments (including gene therapy, immunotherapy, and angiogenesis inhibitors).