How is lung cancer diagnosed?
If lung cancer is suspected, a number of tests will be done to help make a diagnosis.
Some of these tests can also show if cancer has spread to other parts of the body. Not every person will have all the tests described in this booklet. Your doctors will determine the best tests for you.
Imaging tests
Chest x-ray
An x-ray of the chest can show tumours as small as 1cm wide.
Occasionally a tumour is found on a chest x-ray that has been taken for other reasons. X-rays are painless and effective in identifying tumours, but sometimes small, hidden tumours don't show up on the x-ray.
Example of an x-ray showing a lung cancer tumour:
CT scan
A computerised tomography (CT) scan is a special type of x-ray that gives a three-dimensional picture of the organs and other structures (including any tumour) in your body. This test is painless.
CT scans are usually done at a hospital or a radiology service. They help:
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identify smaller tumours than those found by x-rays
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assess whether lymph nodes are enlarged
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determine whether the cancer may have spread to other parts of the body.
A CT scan usually takes less than 10 minutes. You will be asked to lie flat on a table while the CT scanner, which is large and round like a doughnut, rotates around you.
Before the scan, a dye may be injected into a vein, probably in your arm. This will make the scanner’s pictures clearer.
You will be asked not to eat or drink for a while before your scan. Most people are able to go home as soon as their scan is done.
PET scan
A positron emission tomography (PET) scan is a specialised imaging test that is available in only some hospitals.
- You will have an injection of a radioactive glucose solution.
- The glucose circulates the body.
- Active cells, like cancer cells, may take up more of this glucose solution.
The PET scan is useful in diagnosing lung tumours where a biopsy is not possible. It is also very helpful in staging lung cancer, and finding cancer that might have spread to other body organs, such as the lymph nodes, bones, brain, liver and adrenal glands.
Bone scan
In a bone scan, a small amount of radioactive substance is injected into a vein. It travels through the body and collects in areas of abnormal bone growth. A scanner measures the radioactivity levels in these areas and records them on x-ray film.
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Test is often used after cancer has been diagnosed -- it can identify spread of cancer to the bones.
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Sometimes done if the patient is complaining of pain and aches in their bones and joints.
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A bone scan might identify a spread of the cancer to the bones.
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Takes several hours.
Brain scan
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The brain scan is most useful once lung cancer has been diagnosed.
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Sometimes used if the patient is complaining of unexplained symptoms such as headaches and dizziness.
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A brain scan might identify a spread of the cancer to the brain.
Tissue sampling tests
Sputum cytology
The sputum cytology test is an examination of sputum (liquid phlegm coughed up from lungs) under a microscope to check for abnormal cells.
You can collect sputum samples by coughing deeply to bring up sputum from your lungs. You can do this at home, storing the sample in the fridge before taking it to the doctor or pathology collection centre.
Brushing and washing
If a lung tumour is near your main respiratory tract, the cells that line the respiratory tract can be sampled using a collection technique process called brushing and washing. This is done during a bronchoscopy.
- In "washing", a small amount of fluid is injected into the lungs and then withdrawn.
- The sample is examined under a microscope.
- "Brushing" is when the tool lifts some cells from the lining of the bronchi.
Bronchial biopsy
If a tumour can be seen in your airway during a bronchoscopy, a biopsy might be taken. A sample of tissue from your lungs is examined under the microscope.
Fine-needle aspiration
A fine-needle aspiration biopsy is done when tumours are accessible (in the outer parts of the lung). Not every tumour can be safely sampled this way.
- The procedure is done in a hospital or radiology department.
- A local anaesthetic is injected into the skin and, under the guidance of an x-ray machine, a needle is inserted through the chest wall and into the tumour.
- Cells are withdrawn through the needle.
- You will be observed afterwards because the lung is at risk of being punctured during this procedure.
A procedure called thoracentesis also uses a fine needle. Instead of going into the tumour, fluid from between the membranes that cover the lungs (the pleural space) is sampled to check for cancer cells.
Tests to look at growth
Bronchoscopy
Bronchoscopy allows the doctor to look directly into your bronchi (airways). The bronchoscope can only look at the larger airways, so if the tumour is in the outer part of the lung, it may not be seen.
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You will be given a light sedative.
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A flexible tube called a bronchoscope is inserted through the nose or windpipe.
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A sample of tissue (biopsy) may be taken during the bronchoscopy.
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Can be uncomfortable, but it shouldn't be painful.
Mediastinoscopy
A mediastinoscopy is a procedure that allows a cardiothoracic surgeon to examine lymph nodes at the centre of your chest (and remove a sample, if necessary).
- You will have a general anaesthetic/
- A rigid tube is inserted through a cut in your neck and down the windpipe (trachea).
- The surgeon inspects the area between the lungs (mediastinum).
- Usually a day procedure in hospital, but you may have to stay overnight.
Video-assisted thoracoscopic surgery
Thoracoscopes are instruments like bronchoscopes and mediastinoscopes. The doctors can see inside your chest using these instruments, and take tissue samples if necessary.
A small video camera guides the surgeon, who watches a video screen. You may have up to three small cuts in your chest, one for the camera and two for the surgical instruments. You will have a general anaesthetic and be in hospital for 2-3 days.
Thoracotomy
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A thoracotomy is a major operation performed under a general anaesthetic.
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The cardiothoracic surgeon opens the chest cavity through a cut on the back and examines, biopsies and/or removes the tumour.
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It is only required when all other tests fail to provide a diagnosis.
Other tests
You may also have blood and breathing tests.
If surgery is being planned, it is important to check that you are fit to have an operation, particularly that your breathing capacity is good enough. Some people who smoke develop a condition called emphysema, in which the alveoli of the lungs are enlarged and damaged. They may have reduced breathing capacity.
