Mesothelioma

How cancer develops

          

About mesothelioma

The mesothelium is a thin layer of cells (mesothelial cells) that surrounds some of the organs in your body. If you have mesothelioma, your mesothelium thickens because of an abnormal and uncontrolled growth of cells. This causes your mesothelium to restrict the organ it surrounds. Fluid can also collect between the inner and outer layers of your mesothelium, which can put pressure on surrounding tissues and organs.

Most mesotheliomas are cancerous (malignant). A type of non-cancerous (benign) mesothelioma can develop in the lining of your lungs, or in the lining of your reproductive organs, but this is rare. This information describes cancerous mesothelioma only.

In the UK, about 2,500 people get mesothelioma each year. Mesothelioma is five times more common in men than women.

Types of mesothelioma

There are two main types of mesothelioma.

  • Pleural mesothelioma. This affects the mesothelium surrounding your lungs, which is called the pleura. It's the most common type of mesothelioma. Sometimes, pleural mesothelioma can spread to the mesothelium surrounding your heart, which is called the pericardium.
  • Peritoneal mesothelioma. This affects the mesothelium surrounding your abdomen (tummy), which is called the peritoneum. It’s a much rarer form. Peritoneal mesothelioma doesn't spread to other parts of your body.

Symptoms of mesothelioma

General symptoms of mesothelioma include:

  • fever
  • sweating, particularly at night
  • unexplained weight loss
  • feeling tired

If you have pleural mesothelioma, you may:

  • have chest or back pain
  • feel breathless
  • have a cough that won’t go away
  • have a hoarse voice
  • have difficulty swallowing

If you have peritoneal mesothelioma, you may:

  • have a swollen abdomen
  • have pain in your abdomen
  • lose your appetite
  • have diarrhoea or constipation
  • feel sick and vomit

These symptoms aren't always caused by mesothelioma but if you have them, see your GP.

Causes of mesothelioma

Seven to eight out of 10 people with mesothelioma have previously been exposed to asbestos, which is a type of mineral. Asbestos is made up of tiny fibres which, when breathed in, pass into your lungs. Here they cause inflammation and fibrous tissues to form. As your body tries to remove these fibres from your lungs, they pass into other areas such as your mesothelium.

Asbestos was used in construction, ship building and household appliances until 1999, when it was banned. Mesothelioma is therefore common in people who worked as carpenters, electricians, mechanics and plumbers before 1999.

Mesothelioma caused by asbestos takes between 15 and 40 years to develop. Because of this, doctors predict that an increasing number of people will be diagnosed with this condition over the coming years.

It’s not fully understood what causes mesothelioma in people who haven't been exposed to asbestos. However, certain factors can make mesothelioma more likely to develop, including:

  • exposure to a particular type of radiation
  • exposure to zeolite (a type of mineral)
  • previous infection with the Simian monkey virus (SV40)

Diagnosis of mesothelioma

Your GP will ask you about your symptoms and examine you. He or she may ask you to have a chest or abdominal X-ray. Depending on the result, your GP may then refer you to a doctor who specialises in conditions affecting the lungs, or a gastroenterologist (a doctor who specialises in conditions of the digestive system).

The tests and investigations you need to have may include the following.

  • Scans. These may include CT, MRI, PET (positron emission tomography, which is a type of three-dimensional imaging technique) or ultrasound scans.
  • Fluid drainage. Your doctor will take a sample of the fluid from around your lungs, or in your abdomen, and send it to a laboratory for testing. This procedure is called pleural or peritoneal aspiration and is usually done under local anaesthesia.
  • Biopsy. Your doctor will take a sample of cells from your lungs or abdomen and send them to a laboratory for testing. This may involve having a small tube with a camera on (an endoscope) put in through a small cut in your chest. The procedure can be done under local or general anaesthesia.
  • Mediastinoscopy. Your doctor will place a flexible, narrow tube through a cut in your neck to look for mesothelioma in your mediastinum (the space in between your lungs). This procedure is done under general anaesthesia.

Treatment of mesothelioma

The treatment of mesothelioma depends on how advanced it is. As mesothelioma tends to spread invasively into surrounding tissues, treatment is generally aimed at slowing or shrinking the cancer and controlling symptoms.

Medicines

Your doctor may prescribe you painkillers or steroid medicines. Steroid medicines, such as prednisolone can reduce inflammation, improve your appetite and make you feel less tired. If you have a build up of fluid in your abdomen, your doctor may prescribe you a medicine called a diuretic, which makes you pass urine more often. Always ask your doctor for advice and read the patient information leaflet that comes with your medicine.

Non-surgical treatments

Chemotherapy
Chemotherapy is a treatment that uses medicines to destroy cancer cells. The medicines are usually injected into a vein but sometimes you may take them as tablets. Chemotherapy can be given alone, or alongside surgery or radiotherapy, to control or shrink the cancer.

The most common chemotherapy medicines used to treat pleural mesothelioma are a combination of pemetrexed and cisplatin. You will usually have to take supplements of folic acid and vitamin B12 alongside this treatment. If you have peritoneal mesothelioma, your doctor may suggest a chemotherapy treatment like the one given for pleural mesothelioma. Alternatively, he or she may advise you to take part in a clinical trial to test a new chemotherapy medicine, which is given straight into your abdomen through a tube, in a procedure called cytoreductive surgery.

Radiotherapy
Radiotherapy uses X-rays to destroy cancer cells. It's generally only used to treat pleural mesothelioma, either to stop the cancer returning after you’ve had surgery or to stop it spreading in the area where your biopsy was taken. Radiotherapy may be offered as part of a clinical trial.

Fluid drainage
Excess fluid around your lungs or on your abdomen can be regularly drained under local anaesthesia using a needle. Alternatively, you can have a tube more permanently put into the space where the fluid collects around your lungs. This is called an indwelling pleural catheter. It’s left in place, hidden under clothing, so that fluid can be drained off whenever necessary, either by you or a district nurse.

Pleurodesis
In this procedure, your doctor puts chemical powders into your pleural space through a tube. The powders inflame the layers of your mesothelium, which makes them stick together so that fluid can't build up between them again.

Surgery

There are several different types of surgery for mesothelioma, depending on which type you have and how advanced it is. The benefit of surgery for most people who have mesothelioma remains contested.

Surgery for pleural mesothelioma

  • Pleurectomy. This is an operation to remove as much of the pleural mesothelioma as possible to help control your symptoms. This operation can stop the build-up of fluid around your lungs, reduce pain and stop you feeling breathless.
  • Extrapleural pneumonectomy. This is an operation to remove the whole pleura, your diaphragm, pericardium and your affected lung. However, it’s a major operation and is rarely used to treat mesothelioma.

Surgery for peritoneal mesothelioma
Surgery is rarely used to treat peritoneal mesothelioma. However, occasionally, your peritoneum can be removed in an operation called a peritonectomy.

Physical therapies

You may find physiotherapy, and breathing and relaxation techniques helpful. Your doctor may refer you to palliative care services to help you control your symptoms and maintain your quality of life.

Help and support

Your doctor will be able to put you in contact with specialist help and support.

If you have mesothelioma because you have been exposed to asbestos, you may be entitled to compensation, either through government benefits and/or suing your employer. Your doctor may be able to put you in contact with a law firm that specialises in asbestos claims. Alternatively, you can contact your local Citizens' Advice bureau for more information.

Does smoking cause mesothelioma?

Answer

No, there isn't any evidence linking smoking to mesothelioma.

Explanation

There is no research showing that smoking causes mesothelioma. There is, however, lots of scientific evidence to show that exposure to asbestos causes mesothelioma. If you have worked in an environment with asbestos, this may be the cause of your mesothelioma.

You don't even need to have had direct contact with asbestos in the workplace to develop mesothelioma. For example, you may have breathed in fibres from clothes worn by a family member who worked with asbestos or who had been in contact with asbestos.

If you or a family member have been in contact with asbestos and think you may have symptoms of mesothelioma, contact your GP.

Is mesothelioma genetic and if so, could I have passed it on to my children?

Answer

No, there's no evidence that you can pass mesothelioma on to your children.

Explanation

Faulty genes don't cause mesothelioma so you can't pass it on to your children. Breathing in asbestos fibres is the main cause of mesothelioma. There are a number of other factors that may be linked to mesothelioma, including:

  • exposure to particular types of radiation
  • exposure to a mineral called zeolite
  • previous infection with the Simian monkey virus (SV40)

Speak to your doctor for more information about the causes of mesothelioma.

If mesothelioma can't be treated, what will happen?

Answer

You will be given palliative care to ease your symptoms.

Explanation

By the time most mesotheliomas are diagnosed, the cancer is too advanced to be treated. If this happens, you will be given palliative care. This helps relieve symptoms such as pain and breathing problems, and can improve your quality of life.

The treatment you have will depend on the extent of your mesothelioma and your symptoms. These may include a course of steroids to help with tiredness and weight loss, fluid drainage to ease your breathing or medicines to relieve pain. As well as these treatments, your doctor may suggest:

  • physiotherapy
  • pain control techniques
  • relaxation techniques
  • complementary therapies to help you relax

Being diagnosed with cancer can be distressing for you and your family. An important part of cancer treatment is having support to deal with the emotional aspects as well as the physical symptoms. Specialist cancer doctors and nurses are experts in providing the support you need, and may also visit you at home.