What is cancer?

Cancer is a disease of the cells in the body. The body is made up from millions of tiny cells. There are many different types of cell in the body, and there are many different types of cancer which arise from different types of cell. What all types of cancer have in common is that the cancer cells are abnormal and multiply ‘out of control’.

A malignant tumour is a ‘lump’ or ‘growth’ of tissue made up from cancer cells which continue to multiply. Malignant tumours invade into nearby tissues and organs which can cause damage. Malignant tumours may also spread to other parts of the body. This happens if some cells break off from the first (primary) tumour and are carried in the bloodstream or lymph channels to other parts of the body. These small groups of cells may then multiply to form ‘secondary’ tumours (metastases) in one or more parts of the body. These secondary tumours may then grow, invade and damage nearby tissues, and spread again.

Some cancers are more serious than others, some are more easily treated than others (particularly if diagnosed at an early stage), and some have a better outlook than others.

So, cancer is not just one condition. In each case it is important to know exactly what type of cancer has developed, how large it has become, and whether it has spread. This will enable you to get reliable information on treatment options and outlook.

See leaflet called ‘Cancer – What are Cancer and Tumours?’ for further details about cancer in general.

What is mesothelioma?

Mesothelioma is a type of cancer that occurs in the tissues which cover the lungs or abdomen. The lining around the lungs is the pleura and in the abdomen it is called the peritoneum.

About 2000 people in the UK are diagnosed with mesothelioma each year. Men are five times more likely than women to develop a mesothelioma. It most commonly occurs in people aged between 40 and 70 years.

Mesothelioma most commonly occurs in the pleura – the linings of the lungs. There are two layers of pleura – one lining the lungs and the other lining the chest wall. These two layers have some fluid in between them so they can slide over each other when you breathe in and out easily.

In a similar way, the lining of the abdomen also has two layers – one lining the bowel and abdominal organs and the other lining the abdominal wall. A mesothelioma occurring in the peritoneum is around twelve times less common than a mesothelioma occurring in the pleura.

Very rarely, mesothelioma can occur around the heart or the testes. This leaflet will not discuss these rare types of mesothelioma.

What causes mesothelioma?

A cancerous tumour starts from one abnormal cell. It is thought that something damages or alters certain genes in the cell. This makes the cell abnormal and multiply ‘out of control’. Certain risk factors increase the chance of certain cancers forming. (See separate leaflet called ‘Cancer – What Causes Cancer’ for more details.)

The most important risk factor for getting mesothelioma is being exposed to asbestos in the past. Around nine out of ten people with a mesothelioma have been exposed to asbestos in the past. A mesothelioma may occur 15-20 years after you have been exposed to asbestos.

Compensation is possible if your mesothelioma is due to asbestos exposure. This can be done either through benefits paid by the government or, if you believe your mesothelioma is due to asbestos exposure within a work environment, by suing the employer in question for the period (or periods) during which you were exposed to asbestos.

What is asbestos?

Asbestos is a material that was used in buildings in the past. It is an insulating material that is both heat and fire resistant. There are different types of asbestos; white, brown and blue. Although they are all harmful, blue and brown asbestos are the most strongly linked with mesotheliomas and they have not been imported into the UK since 1985. However, they are still present in some buildings and equipment produced before the ban. White asbestos has been banned in the UK since 1999.

Asbestos materials which are left undisturbed are probably safe. It is asbestos dust or fibres which cause the harm when they are inhaled (breathed in) or ingested (swallowed).

Note: the majority of people who have been exposed to asbestos in the past are not likely to develop mesothelioma. However, it is not possible to identify which people exposed to asbestos are likely to develop mesothelioma in the future. As a general rule, the greater and more prolonged the exposure, the greater the risk.

What are the symptoms of mesothelioma?

The symptoms depend on the site of the mesothelioma. It often takes many years after being exposed to asbestos for mesothelioma to occur.

In the early stages, there may be no symptoms at all. Both types of mesothelioma can cause non-specific symptoms such as increasing tiredness, weight loss, increased sweating and a reduction in your appetite.

When mesothelioma develops in the pleura, this causes the pleura to thicken and may press inwards on the lung.

Symptoms may then include:

  • Shortness of breath. This may be due to the pleura becoming thickened and pressing in towards your lung. In addition, an increase in the amount of fluid may also collect between the two layers of the pleura (a pleural effusion).
  • Chest pain. This can be quite severe and can be due to the mesothelioma pressing on the nerves and even the bones near your lung.
  • Cough.
  • Hoarse voice.

Abdominal swelling may occur if you have mesothelioma in your peritoneum. The lining of the abdomen becomes thickened and fluid can collect in the abdomen (ascites).

If the cancer spreads to other parts of the body then various other symptoms can develop.

How is mesothelioma diagnosed?

It can often be difficult to diagnose mesothelioma, as the initial symptoms can be quite vague. Mesothelioma often starts as a lot of tiny lumps (nodules) in the pleura, which may not show up on scans or X-rays until they are quite large.

The most common initial investigation for a pleural mesothelioma is a chest X-ray. Other scans – for example, CT or MRI scans – are often performed for both types of mesothelioma.

As for all suspected cancers, the diagnosis is usually confirmed by obtaining a small sample or ‘biopsy’. The biopsy is then examined under the microscope to look for the abnormal cells of cancer. One or more of the following procedures may be done to obtain a sample for testing:

  • Fine-needle biopsy. This is where a doctor inserts a thin needle through the chest or abdominal wall to obtain a small sample of tissue. X-ray pictures of the suspected tumour help to guide the doctor to insert the needle into a suspected tumour. The skin is numbed with local anaesthetic to make the test as painless as possible.
  • Pleural tap. If you have an accumulation of fluid between the pleura, some fluid can be drained with a fine needle (similar to the above). The fluid is examined for cancer cells.
  • Ascitic tap. If you have an accumulation of fluid between the peritoneum, some fluid can be drained with a fine needle.

Assessing the extent and spread

If you are confirmed as having mesothelioma, further tests may be done to assess if it has spread. This assessment is called ‘staging’ of the cancer. The aim of staging is to find out:

  • How much the cancer has grown into the lung.
  • Whether the cancer has spread to local lymph nodes or to other areas of the lungs.
  • Whether the cancer has spread to other areas of the body (metastasised).

By finding out the stage of the cancer it helps doctors to advise on the best treatment options. It also gives a reasonable indication of outlook (prognosis). See separate leaflet called ‘Cancer – Staging and Grading Cancer’ for details.

What are the treatment options for mesothelioma?

The treatment for mesothelioma depends on whether or not it has spread. Unfortunately, when mesothelioma is diagnosed, it has usually already spread beyond the point where it could be removed.


An operation may be an option if your mesothelioma is only in one area of your pleura. This operation may involve removing part, or all, of your pleura and part of your lung that is close to it. This type of operation is called a pleurectomy.

It is not yet known if having an operation improves symptoms more or can even help people to live for longer compared with not having an operation. There is a large study currently underway to look at this.

It is much less likely for you to have an operation if you have peritoneal mesothelioma, as this surgery is less likely to cure this type of mesothelioma.


Radiotherapy is a treatment which uses high-energy beams of radiation which are focused on cancerous tissue. This kills cancer cells, or stops cancer cells from multiplying.

Radiotherapy is often used to improve symptoms such as pain or shortness of breath and also to reduce the size of any nodules that may have formed. Radiotherapy may also be given to your chest wall at the place where you have had a biopsy or a drainage tube has been inserted. This can be effective at preventing any mesothelioma from growing out through your chest wall.

See separate leaflet called ‘Radiotherapy’ for more details.


Chemotherapy is a treatment of cancer by using anticancer drugs which kill cancer cells, or stop them from multiplying.

Chemotherapy is sometimes given and can slow the growth of mesothelioma and also improve symptoms you may have.

See separate leaflet called ‘Chemotherapy’ for more details.

Other treatments

If you have recurrent effusions, where the fluid keep building up between the linings of your lungs, then it is possible to have a procedure to reduce the risk of this happening in the future. This is called a pleurodesis. During a pleurodesis, a chest drain to drain the fluid is placed into the space between the linings of your lungs. A chemical is then injected into this space which prevents the fluid forming again. A local anaesthetic is used to numb the skin so it is painless.

You should have a full discussion with a specialist who knows your case. They will be able to give the pros and cons, likely success rate, possible side-effects, and other details about the various possible treatment options for mesothelioma.

What is the prognosis (outlook)?

In general, the outlook is poor. The outlook is best in those who are diagnosed at an early stage when the mesothelioma is still small. An operation may then give a good chance of cure. However, for most people, mesothelioma is diagnosed when it is at a later stage which means that a cure is less likely. For most people with mesothelioma, the expected lifespan after diagnosis is made is usually not more than 1-2 years. However, treatment can often slow down the progression of the mesothelioma.

The treatment of cancer is a developing area of medicine. New treatments continue to be developed and the information on outlook above is very general. The specialist who knows your case can give more accurate information about your particular outlook, and how well your type and stage of mesothelioma is likely to respond to treatment.

Further help and information

Mesothelioma UK

Tel: Freephone 0800 169 2409 Web: www.mesothelioma.uk.com
Mesothelioma UK provides impartial up-to-date information for patients diagnosed with mesothelioma and for their carers.

ADUK (Asbestos Diseases UK)

Tel: 0115 927 5108 Web: www.aduk.org.uk
ADUK was set up by those affected by asbestos exposure. Its provides help and support to those affected by asbestos exposure.

Macmillan Cancer Support

Tel: 0808 800 1234 Web: www.macmillan.org.uk
They provide information and support to anyone affected by cancer.

Cancer Research UK

Their website www.cancerhelp.org.uk provides facts about cancer, including treatment choices.

References and Disclaimer | Provide feedback



Leave a Reply

Your email address will not be published. Required fields are marked *