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How is mesothelioma diagnosed?

In this section, we explain how mesothelioma is diagnosed and what to expect from the different tests you may have. We also explain the different stages of this type of cancer.

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If your doctor thinks you might have mesothelioma, the first step is usually a chest X-ray. You should have the X-ray within two weeks, and after that you should receive your results within five working days.

If you have mesothelioma, a chest X-ray will often show a pleural effusion (a build-up of fluid) on one side of your chest. There are many possible causes of pleural effusion. If there’s no clear explanation, your doctor should refer you to a lung specialist for further tests to find out the cause. 

In some cases of mesothelioma, the chest X-ray looks normal. In this case, you would need further tests to confirm whether you have mesothelioma. If you have symptoms and think you have been exposed to asbestos, you should ask your GP for a referral to a lung specialist.

Rapid access clinic

If your chest X-ray shows signs that you might have mesothelioma, you’ll be referred to a special clinic at the hospital called the rapid access clinic or urgent cancer clinic. These services are set up to confirm if you have mesothelioma or not, and provide specialist advice and treatment.

Your first appointment with the specialist lung doctor

You may want to bring a partner or friend with you to this appointment – it’s good to have moral support and they can help you remember what the doctor says. If you live in England, your first appointment with a specialist should be within two weeks of your GP referral.

At your first appointment, you’ll usually see a specialist lung doctor. They’ll examine you and ask about your symptoms and medical history. You can help by bringing a list of any medicines you’re taking. They may also ask about your job history (and your partner’s) to try and find out if you might have been exposed to asbestos.

The doctor will explain the results of any tests you’ve had so far. You may have already had a CT scan – most clinics offer this before your first specialist appointment. If you’ve not already had a CT scan, they’ll organise one for you and will tell you about any other tests you might need.

Usually, you’ll be offered the opportunity to meet a specialist cancer nurse. This nurse is there to help arrange your tests and provide you with further information. They’ll give you their contact details so you can get in touch if you have any questions or worries.

The multidisciplinary team

The doctor and nurse you see at your first appointment are part of a multidisciplinary team. This is a group of health care professionals who specialise in diagnosing and treating mesothelioma. It also includes X-ray specialists called radiologists, cancer specialists called oncologists, and surgeons. They meet every week to discuss your test results and plan your care.

Since mesothelioma is not as common as other cancers, multidisciplinary teams might not have a lot of experience in diagnosing and treating it. Some hospitals have come together to develop regional mesothelioma specialist multidisciplinary teams. There’s some evidence that these specialist teams offer a wider range of treatment options and access to clinical trials. You should ask if there’s a mesothelioma specialist multidisciplinary team in your area that can be involved in your care.

You should be offered follow-up appointments every three to four months with an oncologist, respiratory physician or specialist nurse, depending on your treatment plan. If you wish to be seen less frequently, you should be offered the option of regular telephone follow-up in between face to face visits.

Further tests

It can be difficult to diagnose mesothelioma. As well as a chest X-ray, you’ll probably need to have a few different tests. These tests will help to answer the following questions:

  • What is it? Is it definitely mesothelioma and if so, what type is it?
  • Where is it? Is the tumour only in your chest or has it spread? This is known as the stage. 
  • What do we do about it? What are your treatment options?

The tests may include a CT scan, MRI scan, PET scan and biopsy as well as blood samples and breathing tests.

CT scan

After a chest X-ray, a CT scan is the next key step to diagnose mesothelioma. A CT scan is done using a special X-ray machine which produces a detailed image of your chest and of the other organs that the cancer can spread to. 

Before the scan, you’ll be given an injection in your hand. The injection contains a dye called iodine, so you will be asked if you are allergic to iodine. You’ll then be passed through a doughnut-shaped scanner while lying on a flat bed. The scan only takes a few minutes and you won’t be inside a tunnel so you shouldn’t feel claustrophobic.

The CT scan gives your doctor more reliable information about whether you have mesothelioma and how advanced it is. But it’s not always conclusive. Usually you’ll need further tests involving a biopsy to confirm if the cause is mesothelioma.

MRI scan

You may also be offered an MRI scan. This scan uses strong magnetic fields and radio waves to produce detailed images of the inside of your body.

PET scan

Some people may be asked to have a PET scan. This is like a CT scan, but with a different sort of dye injected into your hand.


To confirm you have mesothelioma, and which type you have, your doctor will probably need to take a sample of fluid or tissue for testing. This is called a biopsy. There are a few different types of biopsy, but the most common techniques are a pleural aspiration, thoracoscopy, or percutaneous biopsy.

  • Pleural aspiration or tap. The doctor inserts a thin needle through your skin and into the pleural space around your lungs. They’ll usually use an ultrasound scan to identify the best area to insert the needle. They’ll then take a sample of the fluid. This sample goes to the laboratory for testing. Sometimes your doctor might drain a lot of the fluid to relieve symptoms if it’s making you feel very out of breath. It’s normally carried out with a local anaesthetic, but it’s not a very painful procedure so is sometimes done without anaesthetic.
  • Thoracoscopy. This test is often used if you have a pleural effusion (fluid buildup in the pleural space). The doctor uses a flexible camera called a thoracoscope to look into the pleural space around your lungs. A small cut, about 2cms long, is made in your chest to insert the thoracoscope. Doctors can remove fluid at the same time as taking the biopsy sample. At the same time, sterile talcum powder might be puffed into the chest to try to prevent fluid from building up again in the future. The test is carried out using a local anaesthetic to numb the area and you’ll be sedated to make you feel relaxed. Occasionally it has to be done under general anaesthetic. The procedure is usually done as a day case. But, if you have talcum powder put into your chest you will need to be admitted to hospital and stay in for one or two nights.
  • Percutaneous biopsy. This means taking a sample of tissue from the lining of your lung by passing a thin needle through the wall of your chest. The doctor will use an ultrasound or a CT scan to see the best way in for the needle. They will numb the area with local anaesthetic before taking the biopsy.

The biopsy sample is sent to the laboratory to be examined under a microscope. The results should be available after five to seven days. Sometimes the reading of the biopsy isn’t clear. In this case it might be sent away for a second opinion, which means it will take longer.

What stage is your mesothelioma cancer at?

There are three factors used to work out how far your mesothelioma cancer has developed. This is called finding out what stage the cancer is at:

  • T-stage – how large is the primary Tumour (where the cancer started) and what parts of your chest are affected?
  • N-stage – has the cancer spread to any lymph glands (also called Nodes)?
  • M-stage – has the cancer spread (or 'Metastasised') to other areas in your body?

Once the doctor knows these results, an overall stage will be decided, showing how large the cancer is and whether it has spread around the body. Generally, mesothelioma is divided into four stages. Stage 1 is the earliest stage and stage 4 is the most advanced stage.

You can read more about the stages of mesothelioma on the Cancer Research UK website.

Getting my results

Once mesothelioma is confirmed and the stage has been decided, you’ll see your specialist doctor to discuss your test results and treatment options.
You’ll probably want to ask lots of questions, such as:

  • Will I be cured?
  • What are the side effects of treatment?
  • Should I stop working?
  • Can I still go on holiday?
  • Am I going to die?

No-one will have all the answers, but the specialist doctor will answer your questions as fully as possible. Your specialist nurse can give you additional support and extra information. If you have more questions, or just need to talk, you can call our helpline on 0300 222 5800

How is mesothelioma treated?

Download our mesothelioma information (PDF, 166KB)

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Last medically reviewed: November 2020. Due for review: November 2023

This information uses the best available medical evidence and was produced with the support of people living with lung conditions. Find out how we produce our information. If you’d like to see our references get in touch.