Mesothelioma is a serious type of cancer.  It develops in the lining tissues of the body, most noticeably in the tissues that cover the lungs.  But it can also start in the tissues lining the abdominal cavity (peritoneal mesothelioma).  

These lining tissues are sometimes called the mesothelium.  This is where the cancer, mesothelioma gets its name.  

The pleura

The tissues lining (or covering) the lungs are called the pleura.  There are 2 pleura.  These can be called pleural membranes.  The gap between them is called the pleural space.  The pleura are fibrous sheets.  They help to protect the lungs.  They produce a lubricating fluid that fills the gap between the 2 pleura.  This helps the lungs to move smoothly in the chest when they are inflating and deflating as we breathe.  

The peritoneum

The tissue lining the abdomen is called the peritoneum.  It helps to protect the contents of the abdomen.  It also produces a lubricating fluid.  This helps the organs to move smoothly inside the abdomen as we move around.  

It is unusual for mesothelioma to spread to other parts of the body. But if it does, it does not usually cause troublesome symptoms.

Risks and causes

Mesothelioma is quite a rare cancer but it is becoming more common. It is much more common in men - 85 out of every 100 cases diagnosed are in men.  Pleural mesothelioma  is more common than peritoneal mesothelioma.

Unusually for cancer, we do know what causes the majority of cases of mesothelioma.  It is most often linked to exposure to asbestos.  We have known of a link between asbestos and lung disease since the beginning of the 18th century.  But the link with mesothelioma has only been known since the 1960's.

Many people who develop mesothelioma due to asbestos exposure may be eligible for compensation.  You should talk to a lawyer about this as early as possible.  Your specialist doctor or nurse may be able to give you some information on this from their dealings with other mesothelioma patients.  

There are other factors that can increase your risk of being diagnosed with mesothelioma.  These are

• Radiation 
• Other chemicals

Before screening for any type of cancer can be carried out, doctors must have an accurate test to use.  The test must be reliable in picking up cancers that are there.  And it must not give a positive result in people who do not have cancer. 

If screening were to be introduced for mesothelioma, the test would have to be simple, quick and not too expensive.  Mesothelioma can be difficult to diagnose.  The usual tests for lung diseases often appear to be negative with mesothelioma.  

It would be more cost effective to screen people who are thought to be at a higher risk.  But to do that, we have to be able to identify all those who are at higher risk.  If you think you have been exposed to asbestos in the past, talk to your doctor.  

Symptoms

In its early stages, mesothelioma does not have many symptoms.  When symptoms do develop, they are often caused by the cancer growing and pressing on a nerve or other body organ.

The symptoms of the 2 main types  of mesothelioma are different.

The symptoms of pleural mesothelioma are often defined as:

• Pain in the lower back or the side of the chest 
• A persistent cough 
• Shortness of breath 
• A hoarse or husky voice 
• Losing more than 10% of your weight when not dieting 
• Sweating and fevers 
• Difficulty swallowing

The symptoms of peritoneal mesothelioma are:

• Pain in the abdomen (tummy) 
• Swelling in the abdomen 
• Feeling or being sick 
• Poor appetite 
• Losing more than 10% of your weight when not dieting 
• Diarrhea or constipation

These symptoms are all more likely to be caused by some other illness, rather than by mesothelioma.  But if you have these symptoms, see your doctor.  This is particularly important if you have been exposed to asbestos in the past.

Types

There are 2 main types of mesothelioma

• Pleural mesothelioma 
• Peritoneal mesothelioma

The pleural type grows in the tissues covering the lungs.  The peritoneal type grows in the tissue lining the inside of the abdomen (stomach).   Pleural mesothelioma is much more common than peritoneal mesothelioma.  

Between 8 and 9 out of 10 (80-90%) cases of mesothelioma are pleural mesothelioma and the rest are peritoneal.

Cell types

Mesothelioma is also grouped according to how the cells look under a microscope.  When mesothelioma is grouped this way, there are 3 types:

• Epitheloid 
• Sarcomatoid or fibrous 
• Mixed type (also called Biphasic type)

Between 5 and 7 out of 10 cases (50-70%) of mesothelioma diagnosed are the epitheloid type.

Between 7 and 20 out of every 100 cases (7 – 20%) of mesothelioma diagnosed are sarcomatoid type.

Between 20 and 35 out of every 100 cases (20 – 35%) of mesothelioma diagnosed are mixed and have both epitheloid and sarcomatoid cells.