Lung cancer tests

To investigate abnormal symptoms, your doctor may arrange several imaging tests.

Chest x-ray

A chest x-ray is painless and can show tumours 1 cm wide or larger. Small tumours may not show up on an x-ray or may be hidden by other organs within the chest cavity. After a chest x-ray, you may need more detailed tests.

CT scan

A CT (computerised tomography) scan uses x-ray beams to take many pictures of the inside of your body and uses a computer to compile them into one detailed, cross-sectional picture. It 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 a radiology clinic. You may be asked to fast (not eat or drink) for several hours before the scan to make the scan pictures clearer and easier to read.

• Before the scan, you will be given an injection of dye into a vein in your arm. This dye is known as the contrast and it makes the pictures clearer. The dye 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. The dye usually contains iodine. If you have had an allergic reaction to iodine or dyes during a previous scan, let the person performing the scan know in advance. You should also let them know if you are diabetic, have kidney disease or are pregnant.
• The CT scanner is a large, doughnut-shaped machine. You will lie flat on a table that moves in and out of the scanner. The scan itself takes 10–20 minutes, but you will also need to prepare and then wait for the scan. While a CT scan can be noisy, it is painless.

PET scan

A PET (positron emission tomography) scan is a specialised imaging test, which is available at most major hospitals. It is used to stage lung cancer, usually after the diagnosis is confirmed.

• Before the scan, a small amount of radioactive glucose solution will be injected into a vein, usually in your arm. This makes cancer cells show up brighter on the scan because they take up more of the glucose solution than normal cells do.
• You will be asked to sit quietly for 30–90 minutes while the glucose solution moves around your body, then you will lie on a table that moves through the scanning machine. The scan will show ‘hot spots’ that have taken up the high levels of radioactive glucose.

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.

Sputum cytology

A sputum cytology test examines a sample of mucus (sputum) from your lungs. Sputum is different to saliva as it contains cells that line the respiratory passages.

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. The sample can be refrigerated until you take it to your doctor, who will send it to a laboratory to check under a microscope for abnormal cells.

Biopsy

If a tumour is suspected after an x-ray or CT scan, a sample of tissue will be taken to confirm whether you have lung cancer. The sample can be collected in different ways, including:

CT-guided core biopsy 

This is used to obtain cells when the tumour is in the outer parts of the lungs. A CT scan will be used to guide the needle through your chest wall and into position. A small piece of tumour can usually be removed with the needle.

A core biopsy is done in a hospital or radiology clinic. You will be observed for a few hours afterwards, as there is a small risk this procedure can damage the lung.

Bronchoscopy 

A bronchoscopy allows the doctor to look inside the large airways (bronchi). A bronchoscope is passed down your nose or mouth, down your windpipe (trachea) and into the bronchi.

The bronchoscope is a flexible tube with a light and lens for viewing. It may feel uncomfortable, but it shouldn’t be painful. You will be given sedation to help you relax or a general anaesthetic, and the back of your throat will be sprayed with a local anaesthetic to numb it.

If the tumour is near your main respiratory tract, the cells can be collected using the washing or brushing technique. During ‘washing’, a small amount of fluid is injected into the lung and withdrawn for further examination. ‘Brushing’ involves the use of a brush-like instrument to remove some cells from the bronchi.

Endobronchial ultrasound 

An endobronchial ultrasound (EBUS) is a type of bronchoscopy that allows the doctor to see cancers deeper in the lung. Samples may also be taken from a tumour or a lymph node in the middle of the chest or next to the airways. In other cases, samples can be taken from the outer parts of the lung.

The doctor will use a bronchoscope with a small ultrasound probe on the end. The ultrasound probe uses soundwaves to create pictures that show the size and position of the tumour and allow the doctor to measure it. 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.

Mediastinoscopy 

This is not used as often as other biopsy methods, but is sometimes used if a sample is needed from the area between the lungs (mediastinum). A small cut is made in the front of the neck and a rigid tube is passed down the outside of the trachea.

Some tissue is removed from the mediastinal lymph nodes. A mediastinoscopy is usually a day procedure but you may need to stay overnight in hospital for observation.

Thoracoscopy 

It is usually done if other tests are unable to provide a diagnosis. For a thoracoscopy you will have a general anaesthetic.

The surgeon will make one or two small cuts in your chest and insert a surgical instrument called a thoracoscope, which has a camera attached. You will wake up with a drain coming from your side and stay in hospital for a few days.

Gene mutation testing

Genes are found in every cell of the body and inherited from both parents. A change in genes is called a mutation, and this can cause cancer to grow.

A mutation can occur after you are born.

Some genetic mutations have been identified in lung cancers. Tumour tissue from a biopsy can be tested to find a mutation. The results help guide treatment decisions.

Some medicines target particular mutations, so one option may be targeted therapy. However, not all gene mutations associated with lung cancer have a targeted therapy available.