Generally, a general practitioner (GP) is the first doctor a patient will see if they have any of the symptoms experienced with lung cancer. The 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 the person to a specialist – such as a respiratory physician – to run further tests to find the cause of the symptoms.

If lung cancer is diagnosed, a medical oncologist or radiation oncologist will most likely be included in all future treatment decisions of the person.

Tests used in detecting and diagnosing 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. biopsies)
• Tests to determine tumour growth

It is unlikely that a person with suspected or confirmed lung cancer will have all the tests and procedures that are listed here.
The doctor will determine which tests are relevant and necessary for individual patients. The doctor, or other healthcare professional, will be able to fully explain 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 - X-ray

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. The doctor will decide which choice of tests to use, based on other factors such as previous test results and the symptoms of the individual patient.

Chest X-ray:

These can detect tumours as small as 1cm 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.

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

Imaging Tests - CT scan

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 for detecting 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.

 Imaging Tests - 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. 

Imaging Tests - MRI scan

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

Imaging Tests - 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.

Imaging Tests - 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 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. The doctor will decide which choice of tests is required for the individual patient.

Sputum cytology:

Sputum is the liquid substance that is coughed up from the lungs, and 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.

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 machine 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 sample from the fluid between the membranes surrounding the lungs (called the "pleural space"). This procedure is called a thoracentesis.