Mesothelioma

There are two types of mesothelioma - pleural mesothelioma, which effects the pleural cavity that holds the lungs, and peritoneal mesothelioma, which affects the peritoneal cavity near the abdomen.

Mesothelioma can be caused by very short periods of exposure to asbestos. People have developed mesothelioma from working with asbetsos materials for only a couple of hours, from living near a factory which manufactured asbestos materials or from the clothes of their spouse or parent. However, it is a very rare cancer and even those people with high exposures to asbestos do not usually develop the disease.

There is generally a latency period of 15 to 50 years between the exposure to asbestos and the development of the disease.  Indeed, experts will generally not associate an exposure to asbestos that has occured within the last ten years to the development of mesothelioma.

Types of mesothelioma

There are different types of mesothelioma: epithelioid, sarcomatous, and biphasic (a mixture of the first two). The speed at which the disease develops often depends upon which type of mesothelioma it is. Epithelioid mesothelioma is the most common type. It is thought to be more amenable to surgery.

Mesothelioma generally occours in the pleura, although sometimes occurs in the peritoneal cavity.

Symptoms & diagnosis

Symptoms of pleural mesothelioma usually begin with breathlessness, or with back or chest pain, caused by a build up of fluid between the two layers of the pleura surrounding the lung. This build up of fluid is called a pleural effusion. This fluid usually has to be drained from the pleural space to relieve the pressure on the lung. The fluid is then tested. This is called cytology. This alone does not usually prove that mesothelioma is present.

Mesothelioma can be difficult to diagnose. There are other causes of pleural thickening and fluid around the lining of the lung. These conditions can be caused by other cancers, or by infections, or persistent inflammation.

A biopsy, sometimes more than one biopsy, has to be done in order to diagnose mesothelioma. A biopsy involves removing and analysing very small pieces of tissue from the pleura.

There are different types of biopsy: needle biopsy, a needle biopsy guided by CT scan or ultrasound, video assisted thoracoscopic biopsy, in which the surgeon looks into the chest through a telescope and takes samples, and an open biopsy where the surgeon opens the chest cavity and takes samples under direct vision. The pathologist looks at the tissue under the microscope and performs special tests on the tissue to diagnose mesothelioma.

It can sometimes take weeks, or even months, for doctors to diagnose mesothelioma with certainty.

Patients sometimes develop swelling and discomfort at the wound sites where biopsies have been carried out, or surgery performed. Radiotherapy is sometimes used to prevent the tumour spreading in this way and to treat these symptoms if they occur.

In mesothelioma of the lining of the abdomen (peritoneal mesothelioma), patients have swelling of the abdomen resulting from fluid that accumulates. This fluid is called ascites.

People who die of mesothelioma usually die from complications of the disease in the place it originated, usually the chest, and not from it's spread to other parts of the body. The fluid that begins in the pleura is eventually replaced by solid tumour that can cause difficulty breathing, pneumonia or heart problems as well as pain that requires medication itself.