Pleural Mesothelioma

Pleural mesothelioma is a type of cancer which occurs in the outside lining (pleura) of the lungs and the chest cavity lining due to asbestos exposure.  Pleura consist of two layers with a thin space in between that is filled with fluid and serves as organ lubrication.  The inner layer, called the visceral layer, surrounds the lungs.  The outer layer, or parietal layer, lines the entire area inside the chest.

Even though pleural mesothelioma occurs in the lung area, it is not a type of primary lung cancer as it does not originate in the lungs but rather with asbestos settling in the lining of the lungs or chest cavity.  However, pleural mesothelioma can spread into the lungs causing a type of secondary lung cancer.

Pleural mesothelioma is generally caused from breathing in asbestos dust.  The dust or fibers from the asbestos will imbed themselves into the pleura.  When this happens, the imbedded fibers can cause a range of health problems such as inflammation leading to cell destruction and scar tissue build up.1 They can also lead to cancer due to cell mutations in response to the fiber invaders.  Pleura cancer cells, which are mutated cells, will replicate as mutations and grow into large tumors.  These tumors can damage the lungs and also cause fluids to build up between both layers of pleura.

Typically, pleural mesothelioma only occurs in one layer of the pleura, but it can spread to the second layer. It is slightly more common for pleural mesothelioma to occur in the right lung as this lung tends to be larger and thus has a higher surface area of pleural.  Because asbestos tends to settle once inhaled, it is most common for tumors to occur in the lower lung area. Pleural mesothelioma also normally involves multiple tumors and most frequently affects the parietal layer.

Symptoms and Diagnosis

 As with all forms of mesothelioma, there is generally a prolonged latency period for pleural mesothelioma. Cancer is the name given to a group of diseases in which the body’s cells are damaged and then begin to replicate abnormal cells. The mutated cells have damaged DNA. DNA is the cell component that directs cell activity including cell growth and division and even telling the cell when it’s time to die. When the DNA is damaged, the cell doesn’t die when it should and instead begins to divide while maintaining the same DNA damage. In most cases, asbestos is the trigger leading to cell DNA damage in mesothelioma patients.

When the cancerous cells do start to replicate, they will grow into increasingly larger tumors.  Pleural mesothelioma can also lead to a thickening of  the pleura and accumulation of excess fluid  (pleural effusion) in the pleura. Pleural effusion can be caused by cancer (malignant pleural effusion) or it can occur before cancer forms. In either case, the fluid accumulation exerts pressure on the lungs, making it difficult to breath. In fact one of the most common symptoms of pleural mesothelioma is trouble with breathing that may include feeling breathless even while resting. Other common symptoms of pleural mesothelioma include:

  • Pains in chest area (may also appear in areas outside of the chest area such as shoulders, arms or stomach)
  • Chronic dry cough
  • Troubles swallowing
  • Coughing blood
  • Unusual masses underneath skin on chest
  • Unusual weight loss

Diagnosing mesothelioma is difficult and a large enough tissue sample must be taken to determine if the mesothelial process has invaded deep into the thickened pleura.2 Because symptoms usually do not appear until long after asbestos exposure, it is common for the milder symptoms like breathlessness or a dry cough to be ignored or dismissed as symptoms of other minor health problems.  In most cases of diagnosed pleural mesothelioma, patients had symptoms for several months (and sometimes years) but did not bring them to the attention of a doctor.  If you are aware that you have been exposed to asbestos and have any unusual symptoms, you should consult your doctor right away.

If your doctor suspects that your symptoms may be linked to a chest/lung problem, the physician will likely perform an imaging scan, such as an X-ray, CT scan, or MRI.  These scans would show any tumors or pleural effusion. Pleural mesothelioma would then be confirmed with a biopsy and/or a thoracentesis – procedures which are minimally invasive and generally only require a local anesthetic.  A thoracentesis involves the extraction of some of the fluid accumulated in between the pleura linings so it can be closely inspected by a pathologist. The procedure is also used to reduce the amount of pressure on the lungs caused by fluid build-up.

Once Diagnosed with Pleural Mesothelioma

 While pleural mesothelioma is not curable, it can be treated.  Once your doctor confirms pleural mesothelioma and determines its stage, you will be presented with a plan of treatment.  If the pleural mesothelioma is still at an early stage, it may be treatable with pneumonectomy or extrapleural pneumonectomy surgeries.  The pneumonectomy removes part or all of a diseased lung. The extrapleural pneumonectomy removes the lung, the membrane covering the heart, a section of the diaphragm and some of the membrane that lines the chest.4

In most cases, pleural mesothelioma is not diagnosed until it has reached the later stages.  It is much more difficult to treat pleural mesothelioma at later stages because there is a good chance it has spread to other parts of the body.  The most common treatment method at the later stages is chemotherapy.  There are now chemotherapy drugs which are approved for treating pleural mesothelioma.  Radiation therapy can also be used to treat late-stage pleural mesothelioma but often only if combined with surgery and/or chemotherapy.

Patients diagnosed with pleural mesothelioma may be able to take legal action and receive financial compensation.  While financial compensation will not cure your disease, it can provide much-needed resources for paying medical and financial support expenses.  There are specific deadlines in which you must file your claim in order to receive compensation so it is important that you seek legal help quickly after your diagnosis.

References

1 Mesothelioma Information – Inflammatory Immune Response (2010) Retrieved from Mesothelioma Applied Research Foundation at: www.curemeso.org/site/c.kkLUJ7MPKtH/b.4023387/k.643A/Mesothelioma_Information.htm#Inflammatory_Immune_Response

2 Pleural pathology.(2004)  Pathology International, 54: S490–S505. doi: 10.1111/j.1440-1827.2004.01733.x.

3 Seijo, L. M. (2008) Thoracentesis, Percutaneous Needle Biopsy of Pleura, Small-Bore Catheter Drainage: Does Size Really Matter?, in Thoracic Endoscopy: Advances in Interventional Pulmonology (eds M. J. Simoff, D. H. Sterman and A. Ernst), Blackwell Publishing, Malden, Massachusetts, USA. doi: 10.1002/9780470755969.ch14

4 Extrapleural Pneumonectomy. (2011) University of California Medical Center. Retrieved from Division of Adult Cardiothoracic Surgery – General Thoracic Surgery at: thoracic.surgery.ucsf.edu/conditions–procedures/extrapleural-pneumonectomy-.aspx