Mesothelioma

Pleural mesothelioma

The mesothelium (protective membrane) that covers each lung is called the pleura. Mesothelioma that develops in the pleura is called pleural mesothelioma, and accounts for about 92% of mesothelioma cases. Pleural mesothelioma is not the same as lung cancer – it is diagnosed and treated differently.

The pleura

There are 2 layers of tissue in the pleura. The inner layer (the visceral pleura) covers the lung surface, and the outer layer (the parietal pleura) lines the chest wall and diaphragm. Mesothelioma causes these 2 layers of the pleura to thicken. They can then press on the lung, stopping it expanding when you breathe in (inhale).

Between the 2 layers of the pleura is the pleural cavity (also called the pleural space), which normally contains a thin film of fluid. This fluid allows the 2 layers of pleura to slide over each other – so the lungs move smoothly against the chest wall when you breathe. When too much fluid collects in the pleural cavity, it is called pleural effusion.

The respiratory system

Pleural mesothelioma affects the pleura – the membrane that covers the lungs. The lungs are the main organs used for breathing. They are part of the respiratory system, along with the nose, mouth, windpipe (trachea), large airways (bronchi) and smaller airways (bronchioles). The lungs rest on the diaphragm – a wide, thin muscle that helps you to breathe.

Peritoneal mesothelioma

The mesothelium (protective membrane) that covers the organs and lines the walls of the abdomen and pelvis is called the peritoneum.

Mesothelioma that develops in the peritoneum is known as peritoneal mesothelioma. It is far less common than pleural mesothelioma (which is found around the lungs), and accounts for less than 5% of all mesotheliomas.

The peritoneum

There are 2 layers of thin tissue in the peritoneum. The inner layer (the visceral peritoneum) lines the surface of organs such as the bowel, liver and ovaries. The outer layer (the parietal peritoneum) lines the walls of the abdomen and pelvis.

Between the 2 layers of the peritoneum is the peritoneal cavity, which normally contains a very thin film of fluid. This fluid allows the 2 layers to slide over each other. In people with peritoneal mesothelioma, too much fluid often collects between the 2 layers in this cavity. This is called ascites or peritoneal effusion.

The abdomen and pelvis

Peritoneal mesothelioma affects the peritoneum – the membrane that lines the walls and covers the organs of the abdomen and pelvis. These organs include the stomach, bowel, liver, kidneys and, in females, the uterus and ovaries.

In rare cases, mesothelioma can develop in the pericardium, which is a thin, double-layered sac that surrounds the heart. This is called pericardial mesothelioma.

Even more rarely, mesothelioma can occur in the membrane that surrounds the testicles, known as the tunica vaginalis. This is called testicular mesothelioma.

What causes mesothelioma?

Exposure to asbestos fibres or asbestos dust is the cause of almost all (9 out of 10) cases of mesothelioma.

Asbestos is the name for a group of naturally occurring minerals that are resistant to high temperatures and humidity. Asbestos was used in many building products in Australia from the 1940s until 1987. Since 2003, Australia has banned asbestos being sold, reused and/or imported, but it is still found in older buildings, so special care needs to be taken when renovating. It has also been found in some products from overseas.

People who may have been exposed to asbestos at work include: builders, plumbers, gasfitters and electricians; metal-fitters, turners and toolmakers; boilermakers and welders;  steelworkers; asbestos miners; asbestos cement manufacturing workers; insulators; automotive industry workers; mechanics; transport workers (especially waterside workers); telecommunications technicians; marine engineers, shipwrights/boatbuilders; and textile workers.

People cleaning work clothes with asbestos fibres on them, some people who lived in houses containing asbestos, or people spending time in areas where asbestos has been disturbed during renovations or maintenance, can also develop mesothelioma.

It can take many years for mesothelioma to develop after a person is exposed to asbestos. It is often about 50 years after exposure, but may be 10–60 years. This is called the latency period or interval.

How common is mesothelioma?

Australia has one of the highest rates of mesothelioma in the world, with about 800 Australians diagnosed each year. Men make up the majority of cases, with less than a quarter of people diagnosed with mesothelioma being women. This is possibly because asbestos exposure is more common in jobs that were traditionally done by men, such as mining and construction.

Pleural mesothelioma makes up about 92% of cases; peritoneal mesothelioma makes up less than 5% of cases; and other types are even more rare. Mesothelioma is more commonly diagnosed in people aged over 65, but can occur in younger people.

What can I expect?

The plan for what happens if you have mesothelioma can vary from person to person, but is usually as follows:

Diagnosis and staging – You will have various tests to confirm a diagnosis of mesothelioma and work out how far it has progressed. The results will help you and your health professionals make decisions about treatment.

Treatment – Depending on how advanced the mesothelioma is and other factors, treatment may achieve a longer period of disease control and improve quality of life.

Managing symptoms – For many people, the main goal of treatment will be to manage symptoms and improve quality of life. Depending on how mesothelioma affects your health, you may have periods of relatively good health when symptoms are under control or less active. You may also have periods when symptoms need to be relieved with more intensive treatment.

What are the symptoms?

The first signs of mesothelioma are often vague and similar to other conditions. If you are concerned, see your general practitioner (GP). It can take time to be diagnosed, as the symptoms may come and go, and more common conditions are often investigated first. Let your GP know if you think you have been exposed to asbestos in the past. Finding mesothelioma early may mean more treatment options are available to you.

Pleural mesothelioma may cause:

• shortness of breath (breathlessness), which usually feels worse with activity or when you are lying down
• pain in the chest around the ribs or in the shoulder, which may be sharp and stabbing, worse with deep breaths, or dull and persistent
• extra-sensitive skin or change in skin sensation (less common)
• general symptoms such as loss of appetite with weight loss; loss of muscle bulk; fatigue or loss of energy; a persistent cough or a change in coughing pattern; and night sweats.

Peritoneal mesothelioma may cause:

• abdominal pain
• a swollen abdomen
• poor appetite, nausea and vomiting
• unexplained increase in fatigue and low energy
• night sweats or fever
• bowel or urinary problems.

Can I seek compensation?

People who develop mesothelioma due to asbestos exposure may be able to make a claim for compensation. It’s helpful to make notes and talk to family and friends about when and where you may have been exposed to asbestos.

It is important to get advice from an experienced lawyer as soon as possible after diagnosis, because a case for compensation must be started within your lifetime. Mesothelioma or asbestos support groups may be able to help you with more information about seeking compensation.

Which health professionals will I see?

Which health professionals will I see?

Your GP will arrange the first tests to assess your symptoms. If these tests do not rule out mesothelioma, you will usually be referred to a specialist, such as a respiratory physician or gastroenterologist. The specialist will arrange further tests.

If mesothelioma is diagnosed, the specialist will consider the treatment options. Often these will be discussed with other health professionals at what is known as a multidisciplinary team (MDT) meeting. During and after treatment, you will see a range of health professionals who specialise in different aspects of your care.

Health professionals you may see

GP – assists you with treatment decisions and works in partnership with your specialists in providing ongoing care

Respiratory (thoracic) physician – diagnoses diseases of the lungs, including pleural mesothelioma, and recommends ways to treat any symptoms

Gastroenterologist – diagnoses and treats disorders of the digestive system, including peritoneal mesothelioma

Radiologist – analyses x-rays and scans; an interventional radiologist may also perform a biopsy under ultrasound or CT, and deliver some treatments

Pathologist – examines cells and tissue samples to work out the type

Thoracic (respiratory) surgeon – conducts some biopsy procedures and performs surgery to prevent and treat symptoms of pleural mesothelioma, including radical surgery

Surgical oncologist/surgeon specialised in mesothelioma – performs surgery to prevent and treat symptoms of peritoneal mesothelioma

Medical oncologist – treats cancer with drug therapies such as chemotherapy, immunotherapy and targeted therapy (systemic treatment)

Radiation oncologist – treats cancer by prescribing and overseeing a course of radiation therapy

Palliative care specialist – treats pain and other symptoms to maximise wellbeing and improve quality of life

Palliative care team – work closely with the GP and other specialists to help control symptoms such as pain, breathlessness, nausea and anxiety, and maintain quality of life

Nurse – administers drugs and provides care, support and information throughout treatment

Cancer care coordinator – coordinates your care, liaises with other members of the MDT and supports you and your family throughout treatment; care may also be coordinated by a clinical nurse consultant (CNC) or clinical nurse specialist (CNS)

Community nurse – visits you at home to provide medical care and treatment, assesses your needs for supportive care, and liaises with your GP and MDT as required

Dietitian – helps with nutrition concerns and recommends changes to diet during treatment and recovery

Physiotherapist, exercise physiologist, occupational therapist – assist with physical and practical problems, including restoring movement and mobility after treatment and recommending aids and equipment

Social worker – links you to support services and helps you with emotional, practical and financial issue

Psychologist – helps you manage your emotional response to diagnosis and treatment

Initial tests

Blood tests and x-rays can provide information about your overall health and help to rule out other conditions.

Blood test

You will have blood taken to check your general health and let your doctors know how your blood cells, liver and kidneys are working. This helps them work out your fitness for any treatment. Mesothelioma does not usually show up on a blood test, but results may show substances (called tumour markers) that are produced by cancer cells.

X-ray

If you have chest symptoms, you may first have a chest x-ray to look for any changes in the lungs, thickening of the pleura, and fluid in the space between the lungs and the chest wall. If you have abdominal symptoms, an x-ray may look for changes in the abdomen, such as fluid and thickening in the peritoneum.

If fluid, thickening or other changes are found, you will need more tests to check whether mesothelioma or another condition is the cause.

Mesothelioma does not always show up on an x-ray and can be hidden by other organs within the chest cavity. So let your doctor know if you think you may have been exposed to asbestos so that they can investigate further.

Before having scans, tell the doctor if you have any allergies or have had a reaction to contrast during previous scans. You should also let them know if you have diabetes or kidney disease, or are pregnant or breastfeeding.

If mesothelioma is suspected, you will usually have a CT scan. A CT (computerised tomography) scan uses x-ray beams and a computer to take detailed cross-sectional pictures of the inside of your body. Most CT scans are done at a hospital or radiology clinic and you can usually go home as soon as the test is over. You may be asked not to eat or drink (fast) for several hours leading up to having the scan.

Immediately before the scan, you will be given an injection of a liquid dye, called contrast, into a vein, which makes the pictures clearer. The contrast may make you feel flushed or hot all over and leave a bitter taste in your mouth, and you may feel sick or feel a sudden urge to pee. These feelings should pass quickly, but tell someone if you feel unwell.

The CT scanner is a large, doughnut-shaped machine. You will need to lie still on a table while the scanner moves around you. Getting ready for the scan can take 10–30 minutes, but the scan itself takes only a few minutes and is painless. Lying flat and still can be uncomfortable, so speak to your doctor or radiologist about any discomfort.

The CT scan shows the location and thickness of the tumour/s in the chest or abdomen. It may also show if the mesothelioma has spread to other organs. The information from the CT scan is used to work out the best way to get tissue for testing (called a biopsy).

Before having scans, tell the doctor if you have any allergies or have had a reaction to contrast during previous scans. You should also let them know if you have diabetes or kidney disease, or are pregnant or breastfeeding.

Biopsy

A biopsy is the main test used to diagnose mesothelioma. It involves removing a sample of tissue, which is examined under a microscope by a specialist doctor called a pathologist. The pathologist looks for cell changes to work out if the tumour is mesothelioma and the type of cells present. There are 3 main types of mesothelioma cells:

Epithelioid – look similar to normal mesothelial cells. This is the most common type, making up about 75% of cases.

Sarcomatoid (fibrous mesothelioma) – have changed and look like cells from fibrous tissue. This type makes up about 10–15% of cases.

Mixed or biphasic – has epithelioid and sarcomatoid cells. This type makes up about 10% of all cases.

Ways to take a biopsy for mesothelioma

A biopsy can be taken in different ways. The choice of biopsy will depend on your general health and fitness, and how suitable the tumour is for sampling using one of the methods described below.

Keyhole surgery (VATS or laparoscopy) is the most commonly used biopsy technique for mesothelioma, as both tissue samples and fluid can be removed for testing. Obtaining a sample can be challenging, so a respiratory physician or gastroenterologist, radiologist, surgeon and pathologist may all be involved.

Video-assisted thoracoscopic surgery (VATS) – Sometimes called a thoracoscopy, VATS is used to obtain a tissue sample from the lining of the lungs (pleura). You will be given a general anaesthetic, then a thin tube with a light and camera (thoracoscope) will be inserted through a few small cuts in your chest. Tissue samples can be taken through the tube and sent to a laboratory for testing.

If fluid has built up around the lungs and is causing breathlessness, it can be drained during the VATS and you may have a pleurodesis to prevent the fluid building up again. You will usually be given medicine for any pain you feel after VATS.

Laparoscopy – This is used to get a tissue sample from the lining of the abdomen  (peritoneum). You will be given a general anaesthetic, then a thin tube with a light and camera will be inserted through small cuts made in your abdomen. Tissue samples can be removed through the tube and sent to a laboratory for testing. If fluid has built up in the abdomen, it can be drained during the laparoscopy. Any infections that develop will be treated with antibiotics.

CT-guided core biopsy – A CT-guided core biopsy may be used instead of VATS or laparoscopy when there is a large mass but no fluid.

You will be given a local anaesthetic. Using a CT scan for guidance, the doctor inserts a needle through the skin to remove a small piece of tumour from the lining of the lungs or abdomen.

During a CT-guided core biopsy, you will need to lie still on a table for about 30 minutes. You will be monitored for a few hours afterwards. There is a small risk of damaging the lung, but this can be treated if it does occur.

Other tests

PET–CT scan – A PET (positron emission tomography) combined with a CT scan may be used to see how far mesothelioma has spread. It is usually available at major hospitals.

A small amount of radioactive glucose solution is injected into a vein, usually in your arm. You will sit quietly for 30–90 minutes as the glucose solution travels around your body. You then lie on a table that moves through the scanning machine very slowly.

Cancer cells take up more of the glucose solution than normal cells, so they show up brighter on the scan. This test is painless.

Molecular tests and special stains – To confirm a diagnosis of mesothelioma, the pathologist sometimes needs to do further tests on the tissue sample. These are known as molecular tests and special stains. They look for specific molecules that help to tell mesothelioma apart from other types of cancer.

Molecular tests and special stains – To confirm a diagnosis of mesothelioma, the pathologist sometimes needs to do further tests on the tissue sample. These are known as molecular tests and special stains. They look for specific molecules that help to tell mesothelioma apart from other types of cancer.

Draining build-up of fluid

When you first have symptoms of mesothelioma, you are likely to have a build-up of fluid in the space around your lungs or in your abdomen. Fluid around the lungs is called pleural effusion and can make it hard to breathe. Fluid in the abdomen is called ascites and may make it swollen and uncomfortable.

Before further tests or treatment, your doctor may drain the collection of fluid to help ease symptoms. When fluid is drained from the pleura, it is called a pleural tap, pleurocentesis or thoracentesis; when fluid is drained from the peritoneum, it is called a peritoneal tap or paracentesis.

Draining the fluid may be done at the same time as VATS or laparoscopy and the fluid may be tested to look for mesothelioma.

Diagnosis from fluid samples

Sometimes a fluid sample may be used to help make a diagnosis of mesothelioma –  particularly if you are not well enough to have a biopsy. In this case, fluid is collected at the same time as draining the pleural or peritoneal cavity.

It can be hard to diagnose mesothelioma from these fluid samples, because abnormal mesothelioma cells often look similar to other cells. To be as accurate as possible, this technique should be done at a specialist centre. This is because a large volume of fluid must be collected, and the results have to be combined with information from an x-ray and CT scan.

Sometimes, even after several tests, doctors may be unsure of the diagnosis and some tests may need to be repeated. This is common when trying to diagnose mesothelioma.

Staging mesothelioma

If mesothelioma is diagnosed, you will have tests to work out the extent of the disease and if it has spread to other parts of the body. This is called staging, and helps your health care team recommend the best treatment for you. The main tests used are a CT or a PET–CT scan. If you already had a CT or PET–CT scan during diagnosis, which showed advanced disease, a further scan may not be necessary.

Staging systems for mesothelioma

TNM staging system for pleural mesothelioma

The staging system recommended for pleural mesothelioma is the international tumour–node–metastasis or TNM staging system.

T (tumour) 1–4 – Describes if the pleural mesothelioma has grown into the chest wall, diaphragm, lung or beyond. The higher the number, the further it has grown. If limited to the pleura on one side of the chest, it is T1. If it has grown into the lung, chest wall, ribs or diaphragm, lining of the heart or beyond, it is T2, T3 or T4.

N (node) 0–2 – Shows if pleural mesothelioma has spread to lymph nodes. No lymph nodes affected is N0; spread only to lymph nodes in same side of chest is N1; spread to lymph nodes in the other side or centre of chest, or in the neck, is N2.

M (metastasis) 0–1 – Shows if pleural mesothelioma has spread to other parts of the body. M0 means no spread to distant organs; M1 means it has spread to the bones, liver or other distant organs.

PCI system for peritoneal mesothelioma

Peritoneal mesothelioma is usually staged using the peritoneal cancer index (PCI). The area of the abdomen and pelvis is divided into 13 regions. A score out of 3 is given to any tumours found in these regions. The PCI is calculated by adding together the scores for all 13 regions, with a maximum score of 39. The higher the PCI, the further the cancer has spread.

Tests you may have before surgery

If radical surgery is being considered as a suitable treatment option (part of trimodal therapy), you may have other scans and procedures to check whether mesothelioma has spread to other areas of the body. These tests may include:

FDG–PET – A positron emission tomography (PET) scan detects radiation from a low-level radioactive drug that is injected into the body. In an FDG–PET, the drug used is called fluorodeoxyglucose (FDG). The FDG shows up areas of abnormal tissue.

MRI scan – A magnetic resonance imaging (MRI) scan uses a powerful magnet and radio waves to create detailed, cross-sectional pictures of the soft tissues in your body. The noisy, narrow machine makes some people feel anxious or claustrophobic. If you think you may become distressed, mention it beforehand to your medical team. You may be given a mild sedative to help you relax.

Endobronchial ultrasound (EBUS) – This is a type of bronchoscopy that allows the doctor to see the trachea and deep into the lung. It can also take samples of cells from a tumour or lymph nodes in the middle of your chest (mediastinum) or next to the airways, or from the outer parts of the lung. Samples of lymph nodes can help to confirm whether or not they are also affected by cancer. This can help the treatment team to work out the stage of the cancer.

Surgical staging – If it is unclear from the PET–CT scan whether pleural mesothelioma has spread, the surgeon may remove a sample of lymph nodes and tissue from other areas of the body to check. This is known as surgical staging. It is not recommended before a peritonectomy for peritoneal mesothelioma.

Prognosis

Prognosis means the expected outcome of a disease. You may wish to discuss your prognosis with your doctor, but it is not possible for anyone to predict the exact course of the illness.

Mesothelioma behaves differently in different people, which will affect prognosis. The disease is often there for many months before being diagnosed at an advanced stage. After diagnosis, mesothelioma may progress quickly or more slowly. If it progresses slowly, some people may live for several years or longer.

Your doctor will consider several factors when discussing prognosis with you, including:

• the type of mesothelioma cell
• the stage
• the type of treatment you are able to have
• your symptoms, such as weight loss or pain
• your blood count – people with normal levels of blood cells usually have a better prognosis
• your overall health – recovering quickly after procedures tends to suggest a better outcome.

While knowing the stage helps doctors plan treatment, it can’t always indicate a prognosis for people with mesothelioma. This is partly because it is hard to predict how quickly  mesothelioma will grow. Usually the earlier the stage, the better the prognosis.

If the mesothelioma has advanced to a point where it is unlikely to respond to treatment, the priority will be to relieve symptoms and improve your quality of life.