Types of cancer
Diagnosing mesothelioma
Mesothelioma is diagnosed through a series of consultations and tests, starting with a visit to your GP. Learn how these tests work, what the results mean, and how staging guides treatment decisions.
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Sources and references 
Mesothelioma can be difficult to diagnose because the symptoms are similar to other health problems. Mesothelioma cells can look similar to other types of cancer cells or even like normal cells.
The process for diagnosing mesothelioma often starts with seeing a GP or going to hospital with shortness of breath, pain or other symptoms. The doctor will examine you and ask about your health history.
If you think you may have been exposed to asbestos – even if it was a long time ago – it’s important to tell your doctor. They will do initial tests and refer you to a specialist – usually a respiratory physician (for chest symptoms) or a gastroenterologist (for abdominal symptoms).
You are likely to have several tests and see a range of different health professionals before a diagnosis of mesothelioma is made. This process can feel long and frustrating.
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.
CT scan
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).
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
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.
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.
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
The staging system recommended for pleural mesothelioma is the international tumour–node–metastasis or TNM staging system.
TNM staging system for pleural mesothelioma | |
| 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 the 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 with palliative treatment.
Sources and references
Understanding Mesothelioma - A guide for people with cancer, their families and friends
Acknowledgments
This edition has been developed by Cancer Council NSW on behalf of all other state and territory Cancer Councils as part of a National Cancer Information Subcommittee initiative.
All updated content has been clinically reviewed by A/Prof Anthony Linton, Medical Oncologist, Concord Cancer Centre and Concord Repatriation General Hospital, NSW; Dr Naveed Alam, Thoracic Surgeon, St Vincent’s Private Hospital Melbourne and Monash Medical Centre, VIC; Prof David Morris, Peritonectomy Surgeon, St George Hospital and UNSW, NSW.
This edition is based on the previous edition, which was reviewed by the following panel: A/Prof Anthony Linton (see above); Dr Naveed Alam, (see above); Donatella Arnoldo, Consumer; Polly Baldwin, 13 11 20 Consultant, Cancer Council SA; Dr Melvin (Wee Loong) Chin, Medical Oncologist, Sir Charles Gairdner Hospital and National Centre for Asbestos Related Diseases, WA; Prof Kwun Fong, Thoracic and Sleep Physician and Director, UQ Thoracic Research Centre, The Prince Charles Hospital, and Professor of Medicine, The University of Queensland, QLD; Vicki Hamilton OAM, Consumer and CEO, Asbestos Council of Victoria/ GARDS Inc., VIC; Dr Susan Harden, Radiation Oncologist, Peter MacCallum Cancer Centre, VIC; Penny Jacomos, Social Worker, Asbestos Diseases Society of South Australia, SA; Prof Brian Le, Director, Parkville Integrated Palliative Care Service, The Royal Melbourne Hospital and Peter MacCallum Cancer Centre, VIC; Lung Cancer Support Nurses, Lung Foundation Australia; Jocelyn McLean, Mesothelioma Support Coordinator, Asbestos Diseases Research Institute, NSW; Prof David Morris (see above); Joanne Oates, Registered Occupational Therapist, Expert Witness in Dust Diseases, and Director, Evaluate, NSW; Chris Sheppard and Adam Barlow, RMB Lawyers.
We also thank the health professionals, consumers and editorial teams who worked on previous editions of this title. Previous editions of this title and related resources were funded in part by the Heads of Asbestos Coordination Authorities and a donation from Lyall Watts.
Mesothelioma
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