Mesothelioma is a rare form of cancer that affects the thin lining (mesothelium) of the cavities of the body (thoracic, pericardial and abdominal cavities) and the protective outer coating of the organs lodged in these cavities (the lungs in the thoracic cavity, the heart in the pericardial cavity and the abdominal organs in the abdominal cavity). The primary function of this thin cell layer is organ protection. The mesothelium produces a fluid that lubricates the surface of the organs in these body cavities so they move gently in the body.
The mesothelium lining the thoracic cavity and the lungs is called the pleura. Mesothelium lining the abdominal cavity and abdominal organs is called the peritoneum, while that which lines the heart and the cavity where it is lodged is called the pericardium.
In mesothelioma, the cells making up the mesothelium multiply excessively, resulting in the formation of a lump (tumour) and the production of copious amounts of fluid. In the chest this usually involves the outer lining of the lungs and it is called pleural mesothelioma. This is the most common form of mesothelioma.
Most patients with mesothelioma have lived or worked in an area where asbestos was present. The mode of entry into the human body is by inhalation. The inhaled asbestos dust or fibre, over time reaches the mesothelium covering the lungs. This results irritation of the cells, overgrowth of abnormal mesothelial cells and gradual development of pleural mesothelioma. There is often a long time (20-40 years) between exposure to asbestos and development of mesothelioma.
SV40 virus, radiation, and some chemicals present in paint have also been pointed out as possible causes but due to the rarity of these cases, confirming them is difficult.
Signs and symptoms
- Pain somewhere in the chest or back aggravated by breathing
- Shortness of breath. The presence of the lump and the large amount of fluid surrounding the lung limits its full expansion, causing difficulty breathing
- Weight loss
You doctor will perform a physical exam to listen to the lungs and detect the presence of fluid around the lungs. You will then be sent for further tests including:
A chest X-ray will reveal a lump/mass and fluid. Fluid in the pleural or chest cavity is called a pleural effusion.
This is provides 2D images of the chest cavity and can detect tumours and excess fluid in addition to lung collapse. Sometimes a needle biopsy is also done during a CT scan. Under local anaesthesia, a long needle is inserted to where an abnormality is seen, and a tissue sample is aspirated and then sent to the laboratory for microscopic examination.
This is a procedure done in the chest cavity under general anaesthesia. A long camera is carefully inserted into the chest cavity through a small incision in the chest wall. Careful manipulation of the camera enables the surgeon to see inside the chest, in the space between the lung and the chest wall. It is also during this time that the surgeon removes a piece of tissue that lines the inside of the chest wall for a biopsy. During this procedure fluid is also drained from the pleural space. A chest tube is left through one of the small holes to drain any extra fluid after the procedure. Sterile talc may be sprayed inside the chest cavity during the procedure to cause the lung to stick to the inner chest wall and prevent the fluid from re-accumulating.
The management of mesothelioma is complex and requires multi-disciplinary discussion with your lung specialist, your cardiothoracic surgeon and oncologists.