How is lung cancer diagnosed?

In diagnosing lung cancer your doctor will consider your symptoms, ask about your previous and current health, smoking and work history, and do a physical examination. You may then have one or a series of tests which can include a chest x-ray, types of scans and biopsies.

What are the symptoms of lung cancer?

Some people have no symptoms, but learn they have lung cancer when it shows up as a mass or lump on a routine chest x-ray. Others realise something is wrong when new symptoms appear or a bout of bronchitis fails to get better quickly.

Some symptoms are common to other disorders, but they should be checked by a doctor.

The most common symptoms of lung cancer are:

• a cough that does not go away
• repeated bouts of pneumonia or bronchitis
• shortness of breath
• noisy breathing
• pain in the chest and upper back area
• coughing up blood.

In the later stages of lung cancer, people may experience fatigue, loss of weight, extreme shortness of breath, hoarseness, difficulty in swallowing, facial swelling and back pain.

There may also be symptoms that seem unrelated to the lungs. These may be caused by the spread of a lung cancer to other parts of the body.

Diagnostic tests

If lung cancer is suspected, several tests can be used by your doctor to see whether or not cancer is present.

Chest x-ray

An x-ray of the chest can sometimes identify tumours as small as one centimetre in diameter. However, tumours can easily be hidden by surrounding areas of infection and are not always obvious on x-ray.

Sputum cytology

The sputum cytology test is an examination of sputum (phlegm/spit which you cough up from your lungs) under a microscope to check for abnormal cells. You will be asked to collect early-morning samples for several days. To do this you will need to cough deeply to bring up liquid from your lungs. You can do this at home, storing the sample in the fridge before taking it to the laboratory. A negative sputum test does not rule out cancer.

Bronchoscopy

An instrument called a bronchoscope is often used to help diagnose lung cancer, or confirm the type of cancer. The bronchoscope is a flexible tube that can be inserted into the nose or mouth and down the trachea (windpipe). It acts like a periscope and allows the doctor to look in the bronchi and take a sample of any abnormal looking tissue.

The doctor will give you a sedative and a local anaesthetic spray to the back of your throat. If you are still uncomfortable let your doctor know.

Fine-needle aspiration

In fine-needle aspiration, the doctor inserts a needle between the ribs into the tumour. They will use this procedure if you have a suspicious-looking lump that cannot be sampled by bronchoscopy. Fine-needle aspiration is usually done in a hospital.

You will have a local anaesthetic before the doctor inserts the needle through the chest wall into the tumour and removes some tissue. This is nearly always done with the help of a CT scan in the x-ray department.

Thoracentesis

This procedure also uses a fine needle. Instead of the doctor sampling the tumour, they will draw fluid from the pleural space (a space between the two layers of the pleura - which are membranes that line the chest wall and cover the lungs) to check for cancer cells.

Mediastinoscopy

This is a surgical procedure for examining and taking a biopsy of lymph nodes in the mediastinum (the area in the chest cavity between the lungs, that contains the heart and large blood vessels, the oesophagus, the trachea, and many lymph nodes). This test requires a general anaesthetic and a short stay in hospital.

The doctor inserts the viewing scope through an incision (a cut) made above the sternum (the breast-bone).

Video-assisted thoracoscopic surgery

Thoracoscopes are instruments like bronchoscopes and mediastinoscopes. They are inserted into the chest cavity through small incisions in the skin. The doctors can see inside your chest using these instruments, and take tissue samples of anything abnormal.

The doctor can use a very small video camera and is able to guide the instruments by watching the video screen. You may have up to three small cuts made 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 or 3 days.

CT scan

A computerised tomography (CT) scan can be used to assess a tumour more accurately. It can also assess whether lymph nodes are enlarged, or whether other organs are affected. The scan will usually look at your thorax and upper abdomen.

CT scans are a special type of x-ray that give a highly detailed picture of the organs and other structures in your body, and usually give the doctor a much better idea of the size and position of the tumour than a chest x-ray. 

CT scans are usually done at a hospital or a radiology service. It usually takes about 30-40 minutes to complete this painless test. You will be asked to lie flat on a table, while it moves through the CT scanner, which is large and round like a doughnut.

A dye may be injected into a vein, probably in your arm, before the scan. This will make the pictures that the scanner takes clearer. You will be asked not to eat or drink for a while before you have your scan. Most people are able to go home as soon as their scan is over.

Bone scans

If lung cancer is confirmed, a bone scan can help show whether lung cancer has spread to the bones. A small amount of radioactive substance is injected into a vein. It travels through the bloodstream and collects in areas of bone damage. An instrument called a scanner measures the radioactivity levels in these areas and records them on x-ray film. 

The scanner measures the radioactivity levels in all of the bones in the body and produces digital images. The damaged areas show up brighter than normal bone. Damage from arthritis or fractures and some other non-cancer causes can also appear bright.

Positron emission tomography (PET)

Positron emission tomography (PET) scans are being increasingly used before treatment. Before a PET scan a person is injected with a glucose solution (FDG) containing a very small amount of radioactive material. The scanner can ‘see’ the radioactive substance.

Damaged or cancerous cells may show up as areas where the glucose is being taken up. You may have both a PET scan and a CT scan during your appointment.

Other tests

You may also have blood tests and breathing tests. If surgery is contemplated, it is very important to measure your breathing.

'Staging' the cancer

The tests described above show whether you have cancer, its size and whether the cancer cells have spread to other parts of your body. This helps your doctors ‘stage’ the disease so they can work out the best treatment for you.

Non-small cell lung cancer is divided into four stages:

• Stage 1 – small and localised.
• Stage 2 or 3 – has spread into surrounding structures, such as lymph nodes and the chest wall or both.
• Stage 4 – has spread to other parts of the body, such as the liver, bones or brain.

Small-cell lung cancer is divided into two stages:

• Limited disease – the cancer cells can be seen only in one lung, in nearby lymph nodes, or in fluid around the lungs (known as pleural effusion).
• Extensive disease – it is clear that the cancer has spread outside the lung, within the chest area, or to other parts of the body.
  

Your doctors will also consider your general state of health and personal choices when determining treatment options.

Related topics

See also: Treatment of lung cancer;  Lung cancer

What does that term mean?  See Cancer glossary

Original material provided by the Cancer Society of New Zealand, 2010. Edited by everybody, July 2010.