Mesothelioma can be challenging to diagnose. The symptoms are often the same as those of other diseases and mesothelioma cells can look similar to other types of cancer cells.
The path to diagnosis usually begins with seeing your GP or going to a hospital emergency room, perhaps for shortness of breath, pain or another symptom. The doctor will examine you and take a history of your general health. If you think you may have been exposed to asbestos in the past, it is important to raise it at this time as many doctors won't automatically look for mesothelioma. The doctor will arrange some initial tests and probably refer you to a specialist, usually a respiratory physician (for chest symptoms) or a gastroenterologist (for abdominal symptoms).
You are likely to have quite a few tests and see several different health professionals before a diagnosis of mesothelioma is confirmed.
Blood tests and x-rays can provide information about your overall health and help to rule out other conditions.
You will have blood taken to check your overall health and let your doctors know how your blood cells, liver and kidneys are working. This helps them judge your fitness for treatment. A blood test will not usually show up mesothelioma, but can sometimes reveal certain markers that suggest the presence of the disease.
If pleural mesothelioma is suspected, you will have a chest x-ray to look for any abnormalities in the lungs, thickening of the pleura, and fluid in the space between the lungs and the chest wall. For peritoneal mesothelioma, an x-ray will look for abnormalities in the abdomen, such as fluid and thickening in the peritoneum.
If abnormal growth or other changes are found, you will need more tests to check whether mesothelioma or another condition is the cause. Sometimes mesothelioma will not show up on an x-ray but can be seen in a CT scan.
Waiting for test results
Waiting for test results can be a difficult time. It's common to feel anxious about what will happen if you do have mesothelioma. It may help to focus on recovering from the test procedures and any improvements in symptoms.
Some results are available within a few days, but others take several weeks. In some cases, it may be necessary to have more tests before a definitive diagnosis can be made. Ask your doctor or nurse how long the test results will take. It may help to talk to a family member or friend about how you're feeling. They're probably experiencing similar emotions.
If you need support or want to learn more about what a mesothelioma diagnosis will mean for you, call Cancer Council 13 11 20 or contact one of the organisations listed here.
A CT (computerised tomography) scan uses x-rays and a computer to create a detailed picture of an area inside the body.
Before the scan, you will be given an iodine contrast dye to make the scan pictures clearer. This is usually injected into a vein in your arm, but is sometimes given as a drink. If you have had an allergic reaction to iodine or dyes during a previous scan, tell your medical team beforehand. Also let them know if you have diabetes or kidney problems or are pregnant.
For the scan, you will need to lie flat on a table that slides in and out of a large, doughnut-shaped scanner. The procedure takes about 30 minutes. Although the test itself is painless, lying flat and still can be uncomfortable if you already have breathlessness or pain. Discuss any concerns with your medical team.
The CT scan provides accurate information about the location and thickness of the tumour(s) in the chest or abdomen. It can also show if the mesothelioma has spread to other organs. The information gathered by the CT scan is used to work out the best way of obtaining tissue for testing (see Biopsy below).
A biopsy is the main test used to diagnose mesothelioma. A doctor will remove a sample of tissue for a specialist called a pathologist to examine under a microscope. The pathologist can then determine if the tumour is mesothelioma and, if so, the type of mesothelioma cells present. Mesothelioma is usually classified according to the appearance of the cells (although in about 25% of cases, no classification has been recorded):
- Epithelioid – cells look similar to normal mesothelial cells. This is the most common type, making up about 50% of cases.
- Sarcomatoid – cells have changed and look like cells from fibrous tissue. This type accounts for about 13% of cases.
- Mixed or biphasic – has epithelioid and sarcomatoid cells. This type makes up about 12% of all cases. 2
Obtaining a biopsy for diagnosis can be challenging, so a respiratory physician or gastroenterologist, radiologist, surgeon and pathologist may all be involved.
Ways to take a biopsy for mesothelioma
A biopsy can be taken in different ways. Keyhole surgery, such as VATS or laparoscopy, is usually the preferred biopsy technique as several tissue samples can be taken and fluid can be removed. However, the choice will depend on your general health and fitness, and how suitable the tumour is for sampling using this method. An alternative method is CT-guided core biopsy.
Video-assisted thoracoscopic surgery (VATS)
To get a tissue sample from the lining of the lungs (pleura), your doctor may suggest VATS. You will be given a general anaesthetic, then a thin tube with a light and camera will be inserted through several small cuts in your body. Tissue samples can be removed through the tube and sent to a laboratory for analysis. If fluid has built up around the lungs and is causing breathlessness, it can be drained during the VATS.
To get a tissue sample from the lining of the abdomen (peritoneum), your doctor may suggest a laparoscopy. You will be given a general anaesthetic, then a thin tube with a light and camera will be inserted through small cuts on your abdomen. Tissue samples can be removed through the tube and sent to a laboratory for analysis. Fluid that has built up in the abdomen can be drained during the laparoscopy.
CT-guided core biopsy
A CT-guided core biopsy may be used instead of VATS or laparoscopy. You will have a local anaesthetic and the biopsy will be taken from the lining of the lungs or abdomen with a needle that has a tip for cutting out tissue. A CT scan will be used to guide the needle into position.
During a CT-guided core biopsy, you will need to lie still on a table for about 30 minutes. Afterwards you will stay in the radiology suite for a couple of hours so you can be watched for potential complications (such as bleeding or a collapsed lung).
Sometimes to confirm a diagnosis of mesothelioma, the pathologist needs to do further tests on the tissue sample using special stains. These look for specific molecules that may help to distinguish mesothelioma from other cancers.
When you first experience symptoms of mesothelioma, there is likely to be a build-up of fluid in the space around your lungs or in your abdomen. Fluid around the lungs (pleural effusion) can make it hard to breathe. Fluid in the abdomen (ascites) may cause abdominal swelling, shortness of breath and pain.
Your doctor may drain some fluid to provide relief before suggesting further tests or treatment. A sample of the fluid may be sent to a laboratory for testing to see whether cancer cells are present or whether the effusion is caused by another disease.
When fluid is drained from the pleura, it is called a pleural tap, pleurocentesis or thoracentesis; when it is drained from the peritoneum, it is called a peritoneal tap or paracentesis. To prevent fluid building up around the lungs again, you may have a talc pleurodesis at the same time. Read more about these procedures.
Other ways to diagnose mesothelioma
The current clinical practice guidelines recognise that the diagnosis of pleural mesothelioma can be difficult. They recommend CT scan and a biopsy guided by VATS or CT as the most reliable tests. The following techniques are considered less reliable for diagnosing this disease and are not recommended:
- fine needle aspiration, which uses a fine needle to extract sample of cells
- core biopsy (using a needle to remove a sample of tissue)without the guidance of a scan, such as a CT or ultrasound.
Diagnosis from fluid samples
In some cases, a fluid sample rather than a tissue sample may be used to make a diagnosis because it's easy to collect fluid when draining the pleural or peritoneal cavity. However, it can be harder to diagnose mesothelioma with fluid samples, especially as abnormal mesothelioma cells can look similar to cells found in other conditions.
Some specialist centres have developed a high level of expertise in diagnosing mesothelioma using fluid samples. For this method to provide a reliable diagnosis, it's important that the tests are done at a specialist centre, a large volume of fluid has been collected, and the results are combined with information from an x-ray and CT scan. Your doctors may suggest this method of diagnosing mesothelioma if you are not well enough for a biopsy.
After mesothelioma has been diagnosed, your specialist will order further tests to find out if the disease has spread to other parts of the body and, if so, by how much and how far. This process is called staging. Knowing the stage helps doctors to work out your treatment options.
The main test to stage mesothelioma is a CT scan. You may have had a CT scan earlier when mesothelioma was suspected, or during a CT-guided core biopsy. If this CT scan showed advanced disease, a further CT scan may not be necessary.
Staging systems for mesothelioma
Staging is a way to describe the size of the cancer and whether and how far it has spread beyond its original site. Doctors use particular systems when staging different types of 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 in and beyond the pleural cavity. 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 or beyond, it is T2, T3 or T4.
|N (node) 0–3
||Describes if the pleural mesothelioma has spread to the lymph nodes. No lymph nodes affected is N0; spread only to lymph nodes on the same side of the chest is N1; spread to lymph nodes on the other side of the chest or in the neck is N2 or N3.
|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). This gives a score out of 3 for the size of any tumours in 13 regions of the abdomen and pelvis, and then adds the scores together, with a maximum score of 39. The higher the PCI, the further the cancer has spread.
Tests before surgery
If radical surgery is being considered as a treatment option, you may have other scans and procedures to check whether mesothelioma has spread to other areas of the body.
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.
A magnetic resonance imaging (MRI) scan uses magnetic waves to create detailed cross-sectional pictures of the soft tissues in your body.
This procedure is used to sample the lymph nodes at the centre of the chest. A small cut is made in the lower neck, and an instrument is inserted to remove some lymph node tissue from the area between the lungs (mediastinum).
Endobronchial ultrasound (EBUS)
This procedure may be used along with, or instead of, mediastinoscopy. A tube called a bronchoscope, which has a small ultrasound probe on the end, will be put down your throat into your trachea. This allows the respiratory physician to target lymph nodes for biopsy.
Before radical surgery for pleural mesothelioma, a less extensive operation may sample lymph nodes and other areas of the body. Surgical staging is not advised before a peritonectomy for peritoneal mesothelioma.
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. It is often present for many months before being diagnosed at an advanced stage, which will affect prognosis. After diagnosis, mesothelioma may progress quickly or more slowly. If it progresses slowly, some people may live for several years.
Your doctor will consider several factors when discussing prognosis with you, including:
- the appearance of the mesothelioma cells
- the stage
- the type of treatment you are able to have
- your symptoms, such as weight loss or pain
- your white blood cell count – people with normal levels
- 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 is not always useful for working out prognosis for people with mesothelioma. This is partly because it is hard to predict how quickly mesothelioma will grow. In general, the earlier cancer is diagnosed, the better. If the cancer has advanced to a point where it is difficult to treat successfully, the priority will be to relieve symptoms and improve your quality of life.
- Mesothelioma can be very difficult to diagnose since many other diseases have similar symptoms.
- Various tests are used to diagnose mesothelioma. You are likely to need a number of tests before a diagnosis can be confirmed.
- Initial tests usually include a blood test, x-ray and CT scan.
- The main test to diagnose mesothelioma is a biopsy to collect tissue samples. This may be done using keyhole surgery, such as VATS or laparoscopy, or a CT-guided core biopsy. Your specialist will recommend the best technique for you.
- Fluid that has built up in the lungs or abdomen can be drained, either during tests to take a biopsy or as a separate procedure. It is possible to test a sample of this fluid for mesothelioma, but the results may not be reliable unless the test is done in a specialist mesothelioma centre and combined with other tests.
- The main test to see if mesothelioma has spread is a CT scan. If radical surgery is being considered, you may have other types of scans and surgical procedures to work out more precisely how far the cancer has spread (the stage).
- Pleural mesothelioma is staged using the TNM system. Peritoneal mesothelioma uses the PCI system.
- You may wish to talk to your doctor about your prognosis. Prognosis is the expected outcome of a disease.
Expert content reviewers:
Dr Steven Kao, Medical Oncologist, Chris O'Brien Lifehouse, NSW; Theodora Ahilas, Principal, Maurice Blackburn Lawyers, NSW; Prof David Ball, Director, Lung Service, Peter MacCallum Cancer Centre, VIC; Cely Benchoam, Consumer; Prof Kwun Fong, Thoracic Physician, University of Queensland Thoracic Research Centre, The Prince Charles Hospital, QLD; Victoria Keena, Executive Officer, Asbestos Diseases Research Institute, NSW; Angela Kyttaridis, Social Worker, Concord Repatriation General Hospital, NSW; Dr Judith Lacey, Head of Supportive Care and Integrative Medicine, Chris O'Brien Lifehouse, NSW; Amanda Maple, 13 11 20 Consultant, Cancer Council SA; A/Prof Brian McCaughan, Thoracic Surgeon, Sydney Cardiothoracic Surgeons, Strathfield Private Hospital and University of Sydney, NSW; Jocelyn McLean, Mesothelioma Support Coordinator, Asbestos Diseases Research Institute, NSW; Kirsten Mooney, Thoracic Cancer Nurse Coordinator, WA Cancer and Palliative Care Network, Department of Health, WA; Prof David Morris, University of New South Wales, Department of Surgery, St George Public Hospital, NSW; Rod Smith, Awareness and Support Co-ordinator, Bernie Banton Foundation. We also thank the health professionals, consumers and editorial teams who have worked on previous Cancer Council resources.
2. Australian Mesothelioma Registry, Mesothelioma in Australia 2015: 5th annual report, Cancer Institute NSW, Sydney, 2016.