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Diagnostic tests

Lung cancer may be detected in a variety of different ways.xrays Sometimes, there may not be any signs or symptoms of the disease, but it may be discovered during other medical procedures e.g. a chest X-ray during a routine checkup prior to other surgery.

For those people who do experience symptoms, these may give clues to suspect lung cancer, which is then confirmed by medical tests. Others may not have any early signs of the disease, but may go to the doctor due to other symptoms which may indicate advanced stage disease (when the tumour has spread to other parts of the body).

Your general practitioner (GP) is the first doctor you will see if you have any of the symptoms experienced with lung cancer. Your GP may firstly order some tests to investigate these symptoms. If these tests increase the suspicion of lung cancer, or do not rule out lung cancer, the GP will refer you to a respiratory physician to run further tests to find the cause of the symptoms.

dr patientIf lung cancer is diagnosed, a medical oncologist or radiation oncologist may also be involved to work out the best treatment option/s for you to consider.

Tests used to detect and diagnose lung cancer may include:

  • Blood tests
  • Imaging tests (eg. X-ray, Computerised Tomography or CT scan, Magnetic Resonance Imaging or  MRI and Positron Emission Tomography or PET scan)
  • Bone scans – a nuclear scanning test to find abnormalities in bone.
  • Body tissue tests (eg. pathology, sputum cytology and  biopsies)
  • Gene mutation testing
  • Tests to determine tumour growth

Your doctor will determine which tests are relevant and necessary and will be able to fully answer any questions you have about any of the following, or other, medical tests and procedures.

Blood tests

A full blood count is generally taken at the start of any investigation into possible disease, including lung cancer. Changes in the number of red and/or white blood cells help doctors understand if the body is reacting/responding to a disease. Various different naturally occurring substances, such as proteins, antibodies, and the bodies own chemicals may differ from the normal range when cancer is present.

Imaging tests

The following imaging tests are some that may be used when diagnosing lung cancer. Generally, some (not necessarily all) of these tests will be used when identifying lung cancer. Your doctor will decide which choice of tests to use, based on other factors such as previous test results and persistent symptoms.

Chest X-ray

Chest X-rays can detect tumours as small as 1 cm wide. However, sometimes a tumour may be hidden behind another structure e.g. a rib. Further imaging tests are generally required to definitely rule out lung cancer.

healthy Chest x ray lung cancer xray
X-ray of a healthy chest X-ray of a chest with lung cancer. The tumour is circled in yellow.

Fine-needle aspiration

This test may be done if a tumour has been detected in a site close to the chest wall. A local anaesthetic is given into the skin and an X-ray is then used to guide a narrow (“fine”) needle through the skin and into the tumour. A sample of tumour tissue is then taken for microscopic examination. A similar procedure may also be used to collect a sample from the fluid between the membranes surrounding the lungs (called the “pleural space”). This procedure is called a thoracentesis.

CT scan

CT Machine

A computerised tomography (CT) scan gives a 3-dimensional image of the body organs and any other structures, such as a tumour, that may be present.

CT scans are useful to detect tumours in the lungs and chest area that may not be seen on X-ray. They can also detect if the cancer has spread to other parts of the body.

CT scan machines are quite large, and are found in specialist centres such as hospitals or radiology centres. A dye may be injected into a vein prior to the scan, to help the scan pictures to be clearer. The actual scan usually doesn’t take very long (less than 30 minutes) and most people are able to go home after the scan is done.

PET scan

A PET (positron emission tomography) scan is a specialised imaging test. An injection of radioactive glucose is placed into a vein to then circulate throughout the body. The radioactive glucose will form in concentrated quantities around tumour sites, allowing the scan to identify these tumour sites on imaging. This test is useful in determining if the tumour has spread to other parts of the body.

A PET scan of someone with metastatic lung cancer.

MRI scan

An MRI (Magnetic Resonance Imaging) is used to see the internal structure and function of the body. An MRI provides much greater contrast between the different soft tissues of the body than a CT does, making it especially useful in cancer imaging.

Brain scan

This scan is also only used once lung cancer has been diagnosed and if patients have experienced symptoms such as headaches, blackouts, dizziness or seizures. It is used to identify if the cancer has spread to the brain.

Right is a brain scan from a lung cancer patient who has experienced a spread of the disease to the brain. The tumour is highlighted with the arrow.

Bone scan

This scan is usually used once lung cancer has been diagnosed. It also involves the injection of a radioactive substance, which will attach to areas of abnormal growth in the bone. It is used to detect if the cancer has spread to the bones.

This is a bone scan of a patient with small cell lung cancer.

Body tissue tests

Another form of testing used in diagnosing lung cancer is body tissue sample testing. This is where secretions and/or actual tissue (muscles, smooth muscle, body fluids) are taken from the patient and tested in a laboratory, to detect if any, and what type of cancer cells are present e.g. small cell or non-small cell lung cancer cells. As with imaging tests, some (but not necessarily all) of these tests will be used when identifying lung cancer. Your doctor will decide which choice of tests are best for you as an individual.

Sputum cytology

Sputum (phlegm) is the liquid substance that is coughed up from the lungs. Changes in sputum quantity, colour and thickness are commonly seen in lung cancer. This test examines a sputum sample under a microscope to look for abnormal or cancer cells and is useful in detecting changes that are taking place in the lungs. In particular, an early-morning sputum sample is often used, as this is the best time to get a “fresh” sample from fluid which has accumulated overnight.

Bronchial biopsy

If a tumour has been detected in the mouth or trachea during a bronchoscopy, a biopsy (small tissue sample) may be collected for examination under a microscope, to detect changes in individual cells.


A bronchoscopy allows your doctor to look directly into your airways (bronchi), and if required, take biopsy samples of lung tissue. This procedure is performed using a flexible tube called a bronchoscope, which is inserted through your nose or mouth and down your windpipe. The bronchoscope may feel uncomfortable, but it should not be painful.  You will be given either a light sedation or a general anaesthetic and the back of your throat is numbed with a local anaesthetic.

Endobronchial ultrasound (EBUS)

An EBUS is a type of bronchoscopy procedure that allows your doctor to examine and take tissue samples through the airways and windpipe. Your doctor uses a brochoscope with a small ultrasound probe on the end which uses sound waves to create a picture of the body and measure the size and position of a tumour.


This procedure allows a surgeon to examine and sample the lymph nodes at the centre of your chest.  A rigid tube is inserted through a small cut in the front of the neck and passed down the outside of your windpipe.  The surgeon  inspects the areas between the lungs and removes some tissue.


A thoracotomy is usually  done if other tests fail to provide a diagnosis. It’s an operation performed by a surgeon, under general anaesthetic, to take a tissue sample (biopsy) or remove a tumour.

Gene mutation testing

Within each type of lung cancer there are subtypes.  Several lung cancer subtypes can be classified by changes or mutations to specific genes.

By testing for these gene mutations your doctor can tailor your treatment regime for the best outcome. For example, NSCLC patients with certain mutations can significantly benefit from targeted therapies while patients without these mutations gain more benefit from standard chemotherapy. For more information, click here.