Thursday, 21 June, 2007



This page tells you what mesothelioma is. You can scroll down the page to read all the information here. Or you can use these links to go straight down to sections on

* What mesothelioma is
* Mesothelioma in the chest
* Mesothelioma in the abdomen
* Benign (non cancerous) mesothelioma

What mesothelioma is

Mesothelioma is a type of cancer. It is a cancer of mesothelial cells. These cells cover the outer surface of most of our internal body organs, forming a lining that is sometimes called the mesothelium. So this is where this type of cancer gets its name.

Mesothelioma cancer can develop in the tissues covering the

* Lungs
* Abdomen

The pleura

The tissues lining (or covering) the lungs are called the pleura. There are two 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 two pleura. This helps the lungs to move smoothly in the chest when they are inflating and deflating as we breathe.

Mesothelioma is most often diagnosed in the pleura. This is known as pleural mesothelioma. Because it is so close, pleural mesothelioma can also affect the sheet of tissue covering the heart - the pericardium. Doctors call the pericardium the lining, although it is on the outside of the heart. It protects the heart and allows it to move smoothly within the sac that surrounds it. So it does much the same job for the heart as the pleura do for the lungs.

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.

Mesothelioma of the tissues lining the abdominal cavity is known as peritoneal mesothelioma. It is much less common than pleural mesothelioma.

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

Benign mesothelioma

There is a form of non cancerous (benign) mesothelioma that can develop in the lining of the lungs, or in the lining of the reproductive organs. It can occur in either men or women. These non cancerous tumours are very rare and we don't cover them in this section of CancerHelp UK.

Mesothelioma risks and causes

Mesothelioma is quite a rare cancer but it is becoming more common. Just over 2,100 people were diagnosed with mesothelioma in the UK in 2003. There are about 4 times as many cases in men as in women. This is probably because many cases have been caused by exposure to asbestos at work. Pleural mesothelioma is much more common than peritoneal mesothelioma. This page is about the risk factors and possible causes of mesothelioma. You can scroll down the page to read all the information here. Or you can use these links to go straight to sections on

* Asbestos and mesothelioma
* What is asbestos?
* How does asbestos cause mesothelioma?
* Radiation
* Other chemicals
* A virus called SV40

Asbestos and 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. Unfortunately, the number of cases of mesothelioma in the UK each year is expected to rise sharply over the next 20 years because of the heavy use of asbestos in industry from the end of the second world war up until the mid 1970s.

Between 7 and 8 out of every 10 people (70–80%) diagnosed with mesothelioma say they have been in contact with asbestos. Your risk is greater if you were exposed to large amounts of it from an early age for a very long period of time. But there are some patients that say they have no history of any heavy exposure to asbestos.

Remember: Many people who develop mesothelioma due to asbestos exposure may be eligible for compensation. You should talk to a solicitor 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. Or some of the mesothelioma organisations in Help and Support should be able to help.

What is asbestos?
Asbestos is an insulating material that is heat and fire resistant. In the past, asbestos was used widely in the

* Building industry
* Ship building industry
* Manufacture of household appliances
* Motor industry
* Power stations
* Telephone exchanges

So most cases of mesothelioma occur in men who have worked in manufacturing using asbestos or used asbestos products, particularly in construction or engineering. The use of asbestos was very heavy in the years after the war (after 1945). Mesothelioma may not develop until 15 - 40 years after you have been exposed to asbestos, which is why we are seeing an increase in cases now. The number of cases is expected to peak around 2020 and then start to decline.

There are three main types of asbestos: blue, brown and white. Blue and brown asbestos are strongly linked with mesothelioma. They have been banned since the late 1980's and cannot be imported into the UK. White asbestos is now also thought to be harmful. The use of all asbestos was banned in 1999 in the UK.

How does asbestos cause mesothelioma?

Asbestos is made up of tiny fibres. You can breathe these fibres in when you come into contact with asbestos. The fibres work their way into the pleura, lining the lung. They irritate the pleura and damage the cells that the pleura are made of. Some of the fibres that have been breathed in can be coughed up and swallowed. This is probably the cause of peritoneal mesothelioma.

If you have been exposed to asbestos, your family may also have been exposed. Asbestos fibres can be carried home on your clothes. Research studies have confirmed that the family of people exposed to asbestos also have a higher risk of developing mesothelioma.


Pleural and peritoneal mesothelioma has been known to develop after exposure to a type of radiation called thorium dioxide (Thorotast). This was used until the 1950's in some X-ray tests.

Other chemicals

A mineral found in Turkey called Zeolite may cause mesothelioma.

The SV40 virus

There has been some research into a virus called SV40 (the SV stands for 'simian virus'). There is a lot of dispute amongst scientists about this and it isn't generally accepted as a cause. It seems more likely that the virus doesn't cause mesothelioma. It is possible that SV40 may help to increase risk if you've been exposed to another more major risk factor. Doctors call this a 'co-factor'. But SV40 certainly hasn't been proved to be a co-factor so far. In any case, it is far less important a risk factor than asbestos.

Screening for mesothelioma

Screening means testing people for early stages of a disease before they have any symptoms. There is no screening programme for mesothelioma in the UK. 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. Diagnosing mesothelioma can be difficult. The usual tests for lung diseases often appear to be negative with mesothelioma.

As only about 2,000 cases are diagnosed each year, it is not sensible to screen everyone in the country for such a rare disease.

It would be more cost effective to screen people who are thought to be at a higher risk of mesothelioma. But to do that, we have to be alioma. But if you have these symptoms, see your doctor. This is particularly important if you have been exposed to asbestos in the past.

Types of mesothelioma

This page tells you about pleural and peritoneal mesothelioma. Scroll down to read all the text here and find details about where to go for more information on mesothelioma.

Types of mesothelioma
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 (tummy). Pleural mesothelioma is much more common than peritoneal mesothelioma.

Between 7 and 8 out of 10 (70-80%) cases of mesothelioma are pleural mesothelioma. Peritoneal mesothelioma is much less common, making up between 1 and 2 out of every 10 cases (10 - 20%).

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.

These types of mesothelioma cells can further divide into other types of cancerous cells called

* Clear cell
* Small cell
* Acinar cell
* Tubopapillary cell

With so many different types of cells capable of developing into mesothelioma, it makes it very difficult to diagnose this disease.

Should I see a mesothelioma specialist?

This page tells you about the guidelines that GPs have to help them send the right people for pleural mesothelioma tests. There is information below on

* The guidelines
* Urgent chest X-ray
* Urgent referrals to a specialist, within 2 weeks
* What to do if you are still worried

About the guidelines

It can be very difficult for GPs to decide who may have a suspected cancer and who may have something much more minor that will go away on its own.

With many symptoms, it is perfectly right that your GP should ask you to wait to see if they get better or respond to treatment such as antibiotics. If GPs referred everyone who came to see them to a specialist immediately, the system would get jammed and those needing urgent appointments wouldn't be able to get them.

There are particular symptoms that mean your GP should refer you to a specialist straight away. NICE (The National Institute for Health and Clinical Excellence) have produced guidelines for GPs to help them decide which patients need to be seen urgently by a specialist. These Government guidelines on referrals for lung cancer, which includes mesothelioma, were revised in 2005.

The guidelines say that, with some symptoms, you should be sent for an urgent chest X-ray. If that shows anything abnormal, then you should get an appointment to see a specialist. You should ideally see a specialist within two weeks of going to the GP.

There are no guidelines for seeing a specialist for peritoneal mesothelioma. If you know you have been exposed to asbestos in the past, and have unexplained symptoms, you should see your doctor.

When you might need an urgent chest X-ray

You should have an urgent chest X-ray if you have been exposed to asbestos in the past and have any of these symptoms

* New chest pain
* Difficulty breathing
* Unexplained symptoms that last for more than 3 weeks, such as shoulder pain, cough or weight loss

Guidelines for urgent referral

According to Department of Health guidelines, you should ideally get an appointment within 2 weeks for an urgent referral.

You should ideally see a specialist urgently if you have been exposed to asbestos in the past and have recently developed chest pain and shortness of breath.

What to do if you are still worried

If you are concerned that your GP is not taking your symptoms as seriously as you think he or she should, you could print this page and take it along to an appointment. Ask your GP to talk it through with you and then you may be able to decide together whether you need to see a specialist and if so, how soon.

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