Mesothelioma: a Brief Overview

Introduction

Mesothelioma is a cancer which affects the tissue which surrounds and protects various organs in the body. This tissue is called the Mesothelium, and Mesothelioma causes it to become abnormal, divide without control, and invade and damage nearby organs. The most common form is pleural mesothelioma which affects the sac that lines the chest cavity and protects the lungs (the pleura). Other forms are peritoneum mesothelioma (which affects the abdominal cavity) and pericardium mesothelioma (affecting the lining around the heart). The tumours can be either benign (non-cancerous) or malignant (cancerous) although they are most often malignant.

Causes

Mesothelioma is caused by the inhalation of asbestos, a fibrous carcinogenic. These fibres lodge themselves in the lining of the lung affecting the mesothelial cells. Sometimes they cause scarring of the lungs (which is called asbestosis) but this is not cancerous. They can, however, trigger tumour growth between 20 to 50 years after they are inhaled (the average is 35 to 40 years). Asbestos fibres which are swallowed can reach the lining of the abdominal cavity where they play a part in causing peritoneal mesothelioma.

It is generally the case that the longer or more intense the exposure to asbestos the more likely Mesothelioma is to occur. However, there are cases of people getting Mesothelioma years after having worked with it for just a few months. The families of asbestos workers are also at risk as they would possibly have been exposed to asbestos fibres on the clothing of their loved ones.

The dangers of asbestos are now well known, but this was not always the case. Before the 1970s asbestos was a primary insulating material with little or no control in its use or handling. The resulting increase in cases of Mesothelioma is a direct cause of these past practices.

Symptoms

Mesothelioma is often advanced before symptoms occur. This means that the prognosis is not usually very good, with the average survival time for all stages of Malignant Mesothelioma being about one year. Symptoms resemble pneumonia, which coughs, breathing difficulties and abdominal pain being common.

Treatments

Mesothelioma can be treated by chemotherapy, radiotherapy or surgery, or a combination of the three.

Surgery
Extra pleural pneumonectomy is where the entire lung and a portion of the lining of the chest, the diaphragm, and some or the entire sac which surrounds the heart is removed.

Wide local excision targets and removes the cancer and a limited amount of the healthy tissue surrounding the cancerous region.

Pleurectomy and decortication removes part of the covering of the lungs, as well as the lining of the chest and portions of the outside covering of the lungs.

Pleurodesis uses a blend of chemicals and/or drugs to create an intentional scar between the layers of the pleura. Post surgery, the space created by the scar must be drained, using either a catheter or chest tube, and is then filled with a chemical which inhibits the accumulation of fluid in the pleura cavity.

Radiation Therapy
Radiation Therapy uses high energy x-rays to kill cancer cells.

In External radiation therapy a machine emits radiation in a targeted stream at a certain portion of the body.

Internal radiation therapy uses needles, seeds and catheters to place radioactive substance directly on or near the cancer.

Chemotherapy
Chemotherapy uses cancer targeting drugs to stop the cells them from dividing and thus prevent their growth.