Lung cancer

Diagnosing lung cancer

On this page:

Initial tests | Tests to confirm diagnosis | Further tests | Staging lung cancer | Prognosis | Key points about diagnosing lung cancer 


Your doctors will perform a number of tests to make a diagnosis and determine whether the cancer has spread beyond the lung. The test results will help them recommend a treatment plan for you.

Cancer care pathways

For an overview of what to expect during all stages of your cancer care, from diagnosis to treatment and beyond, read or download the Guide to Best Cancer Care  for lung cancer. This resource is also available in Arabic, Chinese, Greek, Hindi, Italian, Tagalog and Vietnamese – see details on the site.

Initial tests

To investigate abnormal symptoms, the first test is usually an x-ray, often followed by a CT scan. You may also have a test to check how your lungs are working and blood tests to check your overall health.

Chest x-ray

A chest x-ray is painless and can show tumours one centimetre wide or larger. Small tumours may not show up on an x-ray or may be hidden by other organs within the chest cavity.

CT scan

A CT (computerised tomography) scan uses x-ray beams to take many pictures of the inside of your body. This scan can detect smaller tumours than those found by chest x-rays, and provides detailed information about the tumour, the lymph nodes in the chest, and other organs.

CT scans are usually done at a hospital or radiology clinic. You may be asked to fast (not eat or drink) for several hours before the scan to make the pictures clearer and easier to read. Before the scan, you will be given an injection of dye into a vein in your arm known as the contrast, which makes the pictures clearer. The contrast may make you feel hot all over and leave a bitter taste in your mouth, and you may feel a sudden urge to pass urine, but these sensations won't last long. 

The CT scanner is a large, doughnut-shaped machine. You will need to lie still on a table while the scanner moves around you. The scan itself is painless and takes only a few minutes, but getting ready for it can take 10–30 minutes.

A low-dose CT scan may be useful for screening healthy people for lung cancer or to follow-up suspicious-looking spots in the lungs. This uses a lower dose of radiation than a regular CT scan and provides a more detailed image than an x-ray.

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

Lung function test (spirometry)

This test checks how well the lungs are working. It measures how much air the lungs can hold and how quickly the lungs can be filled with air and then emptied. You will be asked to take a full breath in and blow out into a machine called a spirometer.

Blood tests

A sample of your blood will be tested to check the number of red blood cells, white blood cells and platelets (full blood count), and to see how well your kidneys and liver are working.

Tests to confirm diagnosis

If a tumour is suspected after an x-ray or CT scan, you will need further tests to work out whether it is lung cancer.


A biopsy is the usual way to confirm lung cancer. A small sample of tissue is taken from the lung and/or the nearby lymph nodes. The biopsy sample is sent to a laboratory, where a specialist doctor called a pathologist looks at the sample under a microscope. There are various ways to take a biopsy:

CT-guided lung biopsy

You will be given local anaesthetic. Using a CT scan for guidance, the doctor inserts a needle through the chest wall to remove a small piece of tumour from the outer part of the lungs. You will be observed for a few hours afterwards, as there is a small risk of damaging the lung. This can be treated if it does occur. 


This allows the doctor to look inside the large airways (bronchi) using a bronchoscope, a flexible tube with a light and camera. You will have sedation or a general anaesthetic, then the doctor will pass the bronchoscope into your nose or mouth, down the trachea (windpipe) and into the bronchi. If the tumour is near the bronchi, samples of cells can be collected with a washing or brushing technique. During "washing", fluid is injected into the lung and removed for examination. "Brushing" uses a brush-like instrument to remove some cells from the bronchi. If the doctor sees a tumour, they will take a sample. 

"I think the doctors knew I had cancer based on the shadow on my CT scan. But they didn't tell me right away. I had to wait two weeks until I had a bronchoscopy and wash." - James

Endobronchial ultrasound (EBUS)

This is a type of bronchoscopy that allows the doctor to see cancers deeper in the lung. It can also take samples of cells from a tumour or a lymph node in the middle of your chest or next to the airways, or from the outer parts of the lung.

You will have sedation or a general anaesthetic, and the doctor will put a bronchoscope with a small ultrasound probe on the end into your mouth. The ultrasound probe uses soundwaves to create pictures that show the size and position of the tumour and allows the doctor to measure it and take samples.

After an EBUS, you may have a sore throat or cough up a small amount of blood. These side effects usually pass quickly, but tell your medical team how you are feeling so they can monitor you.


This is not used as often as other biopsy methods, but is sometimes used if a sample is needed from the lymph nodes found between the lungs (mediastinum). You will have a general anaesthetic, then a small cut (incision) will be made in the front of your neck and a thin tube passed down the outside of the trachea. A mediastinoscopy is usually a day procedure, but you may need to stay overnight in hospital for observation.


If other tests are unable to provide a diagnosis, you may have a thoracoscopy. This uses a thoracoscope, a tube with a light and camera, to take a tissue sample from the lungs. It is usually done under general anaesthetic with a type of keyhole surgery called video-assisted thoracoscopic surgery (VATS). After VATS, you will have a drain coming from your side and stay in hospital for a few days. Sometimes a simpler procedure called a medical thoracoscopy can be done as a day procedure under sedation.

Biopsy of neck lymph nodes

A sample of cells may be taken from the lymph nodes in the neck with a thin needle. This is done using ultrasound for guidance.

Other samples

In some circumstances, such as if you aren't well enough for a biopsy, mucus or fluid from your lungs may be checked for abnormal cells.

Sputum cytology

This test examines a sample of mucus (sputum) from your lungs. Sputum is different to saliva as it contains cells that line the airways. To collect a sample, you will be asked to cough deeply and forcefully into a container. This can be done in the morning at home. You can keep the sample in your fridge until you take it to your doctor, who will send it to a laboratory to check under a microscope.

Pleural tap

Also known as pleurocentesis or thoracentesis, a pleural tap is a procedure to drain fluid from around the lungs. While it is often done to ease breathlessness, the fluid can be tested for cancer cells. It is mostly performed under local anaesthetic using ultrasound for guidance. As with all biopsies, the results need to be interpreted along with the results of physical examination, blood and breathing tests, and imaging tests such as x-ray and CT scan.

Molecular testing

The biopsy sample may be tested for genetic changes or specific proteins in the cancer cells (biomarkers). The tests are known as molecular tests and help work out which drugs may be most effective in treating the cancer.

Genetic changes

Genes are found in every cell of the body and are inherited from both parents. If something triggers the genes to change (mutate), cancer may start growing. A mutation that occurs after you are born is not the same thing as genes inherited from your parents. The most common genetic mutations seen in non-small cell lung cancer are changes in the EGFR (epidermal growth factor receptor), ALK (anaplastic lymphoma kinase) and ROS1 genes. Some mutations can be treated with medicines known as targeted therapy, but others do not yet have a targeted therapy available.


Certain proteins found in some types of non-small cell lung cancer suggest that the cancer may respond to immunotherapy. The most common protein tested for is called PD-L1.

Further tests

If the tests described above show that you have lung cancer, you will have further tests to see whether the cancer has spread to other parts of your body.

PET-CT scan

This scan combines a PET (positron emission tomography) scan with a CT scan in one machine and can provide detailed information about the cancer. A small amount of radioactive glucose solution is injected into a vein, usually in your arm. You will be asked to sit quietly for 30 to 90 minutes while the glucose solution travels around your body, then you will lie on a table that moves through the scanning machine very slowly. Cancer cells take up more of the glucose solution than normal cells do, so they show up more brightly on the scan. Sometimes a PET–CT scan is done to work out if a biopsy is needed or to help guide the biopsy procedure. 

Other tests

You may also have a CT or MRI (magnetic resonance imaging) scan of the brain. If a PET–CT scan is not available or results are unclear, you may have a CT scan of the abdomen or a bone scan. For more information about these tests, talk to your doctor or call Cancer Council 13 11 20.

Staging lung cancer

The tests described above help your specialist work out how far the cancer has spread. This is known as staging, and it helps your health care team recommend the best treatment for you.

TNM system

Non-small cell lung cancer is staged using the TNM system. 

TNM staging system

Lung cancer by stage

  • Stages 1 and 2: early lung cancer
  • Stage 3: locally advanced lung cancer
  • Stage 4: advanced or metastatic lung cancer

Two-stage system

Although the TNM system can be used for small cell lung cancer, doctors usually use a two-stage system:

  • Limited stage: Cancer is only on one side of the chest and in one part of the lung; nearby lymph nodes may also be affected. 
  • Extensive stage: Cancer has spread widely through the lung, to the other lung, to lymph nodes on the other side of the chest or to other areas of the body.


Prognosis means the expected outcome of a disease. You may wish to discuss your prognosis and treatment options with your doctor, but it is not possible for anyone to predict the exact course of the disease. Instead, your doctor can give you an idea about the general outlook for people with the same type and stage of cancer.

To work out your prognosis, your doctor will consider:

  • your test results
  • the type and stage of lung cancer
  • the rate and extent of tumour growth
  • how well you and the cancer respond to treatment
  • other factors such as your age, fitness and overall health,
  • whether you're currently a smoker.

Discussing your prognosis and thinking about the future can be challenging and stressful. It is important to know that although the statistics for lung cancer can be frightening, they are an average and may not apply to your situation. Talk to your doctor about how to interpret any statistics that you come across.

As in most types of cancer, the results of lung cancer treatment tend to be better when the cancer is found and treated early. Newer treatments such as targeted therapy and immunotherapy are effective in some people with advanced lung cancer and are bringing hope to those who have lung cancer that has spread.

To help people with lung cancer receive the best care possible, we have developed an optimal cancer care pathway. View the guide to make sure you get the best care and support at each stage.

Key points about diagnosing lung cancer

Diagnostic tests

The tests to diagnose lung cancer may include:

  • chest x-ray
  • CT scan of the chest
  • lung function and blood tests
  • biopsy – lab tests on a tissue sample removed from your chest by CT-guided lung biopsy, bronchoscopy, endobronchial ultrasound (EBUS), mediastinoscopy or thoracoscopy
  • sputum cytology – tests a sample of mucus from the lungs
  • pleural tap (pleurocentesis or thoracentesis) – tests a sample of fluid drained from the lungs.

Further tests

Other tests can give more information about the cancer, help work out if it has spread and guide treatment. They may include: 

  • molecular tests – tests the biopsy sample to identify genes or proteins in the cancer cells
  • PET–CT scan
  • CT, MRI or bone scans
  • tests before surgery or radiation therapy to check how the lungs are working.

Staging and prognosis

The specialist will tell you the stage of the cancer, which describes how much cancer there is and whether it has spread. You may also wish to discuss the prognosis, which is the expected outcome for people with the same type and stage of cancer as you.

Expert content reviewers:

A/Prof Nick Pavlakis, President, Australasian Lung Cancer Trials Group, President, Clinical Oncology Society of Australia, and Senior Staff Specialist, Department of Medical Oncology, Royal North Shore Hospital, NSW; Dr Naveed Alam, Thoracic Surgeon, St Vincent’s Private Hospital Melbourne, VIC; 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; Renae Grundy, Clinical Nurse Consultant – Lung, Royal Hobart Hospital, TAS; A/Prof Brian Le, Director, Palliative Care, Victorian Comprehensive Cancer Centre – Peter MacCallum Cancer Centre and The Royal Melbourne Hospital, and The University Of Melbourne, VIC; A/Prof Margot Lehman, Senior Radiation Oncologist and Director, Radiation Oncology, Princess Alexandra Hospital, QLD; Susana Lloyd, Consumer; Caitriona Nienaber, 13 11 20 Consultant, Cancer Council WA; Nicole Parkinson, Lung Cancer Support Nurse, Lung Foundation Australia.

Page last updated:

The information on this webpage was adapted from Understanding Lung Cancer - A guide for people with cancer, their families and friends (October 2020). This webpage was last updated in March 2021. 

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