Diagnosing and staging lung cancer

How lung cancer is diagnosed

Lung cancer is a difficult disease to find early and there is no routine screening programme anywhere in the world. For most people, their lung cancer is found after having symptoms for many months while others may have it discovered during a medical check-up.

Often, your GP arranges the first tests to assess your symptoms. It is important to talk about all of your symptoms with your doctor. Then they can work with you to choose the most useful tests to give you a diagnosis and help develop a treatment plan. The most important test is usually a chest X-ray which is quick and simple.

It can be a worrying and tiring time waiting for results, especially if you need several tests. If these tests don't rule out cancer, it's usual to be referred to a lung specialist who will arrange further tests and advise you about treatment options.

The purpose of these tests is to find out the type of lung cancer you have (non-small cell lung cancer or small cell lung cancer) and if the cancer has spread to other parts of your body. Sometimes, you may need to travel to another hospital for some tests. Tests—X-rays, CT scans or PET scans and MRI—are used to make images of the inside of your body to see if you have a lump and if it has spread.

Diagnostic imaging (creating pictures of the inside of your body)

Diagnostic imaging methods are painless tests that create pictures of the inside of your body. This will help your medical team plan the best treatment for you.

Chest X-ray (CXR)

An X-ray of the chest may show cancers one centimetre wide or larger. Small or hidden tumours do not always show up on X-rays, so you may have further tests.

CT scan (previously called a CAT scan)

CT (computerised tomography) scans use X-rays to take 3D (three-dimensional) pictures of the inside of your body. CT scans are usually done at a hospital or radiology service and can be used to find smaller cancers than those found by X-rays. CT scans can also show enlarged lymph nodes or may show cancer in other parts of the body.

You may be asked not to eat or drink for a few hours before the CT scan. A dye (iodine contrast) may be injected into your arm to make the scan pictures clearer. Before the scan, tell your medical team if you're allergic to iodine, fish or dyes, or if you have kidney problems.

A CT scan may take 10 to 30 minutes. You will lie flat on a hard bench which will move you through the centre hole in the CT scanner, a machine shaped like a doughnut.

MRI (Magnetic Resonance Imaging)

This is a scan using magnetic fields and radiowaves to build a picture of the organs inside the body.

The MRI machine is similar to a CT scanner but has a longer central hole more like a cylinder (tube). Scanning is very noisy. Earphones (with or without music) will be offered to reduce the noise.

Some people feel claustrophobic (closed-in) when they are having a scan. If you think this may happen to you, let your doctor know when they book your appointment so you can get medication to help you relax before the scan.

PET scan (Positron Emission Tomography)

PET scans are only available in a few New Zealand cities. A PET scan can be used to help stage lung cancer (see page 36) and look for cancer that may have spread to other parts of the body.

To begin this, a radioactive glucose solution is injected into your arm. It takes 30 to 90 minutes for the body to absorb the radioactive solution. Then you will have two types of scan. One scan looks for where in the body the radioactive glucose solution has built up and the other is a CT scan to match these areas to the different parts within the body. This combination of scans is sensitive and will find areas of the body affected by lung cancer.

If you are a diabetic it is important to have good diabetic control before this test. Talk to your doctor or nurse if your sugar levels are high.

Diagnostic tests

As well as using scans to diagnose cancer, a biopsy to sample cells is also needed.


A pathologist (see Multidisciplinary Care Team) can examine tissue samples to identify the type of lung cancer. Their first aim is to confirm, using a microscope, whether they can see cancer cells.

Sputum cytology

If you're coughing up sputum (phlegm), your doctor may ask you to collect sputum samples at home. You will get a container to collect the sample, which you can then store in your fridge until you take it to your doctor or a laboratory.

The sample of your sputum is tested for cancer cells. Cancer cells are only occasionally found in sputum.


If radiologists (see Multidisciplinary Care Team) find anything abnormal in the lung using diagnostic imaging, a sample of the tissue may be needed to check if it is cancerous. Your doctor will ask you to have a biopsy. A biopsy takes a small sample of tissue from the abnormal area.

There are a few ways to take a biopsy. Your doctor will explain which one is right for you, which will depend on whether the abnormal area is in a lymph gland, in the lung or somewhere else. Exactly how it is done will depend on where it is and what the risks of biopsy are.

For abnormal areas in the lung that cannot be reached by bronchoscopy, doctors often use a "core biopsy" because it can give a very clear diagnosis.

A radiologist uses an ultrasound or CT scan to find the area and puts a small needle through the skin and through the lung to take a core biopsy sample. Before they do the biopsy, you will have a local anaesthetic.


During a bronchoscopy the doctor looks into the airways (bronchi) and biopsies any abnormal areas seen.

Doctors use a flexible tube called a bronchoscope, which is put into your nose or mouth and down your windpipe (trachea). The bronchoscope may feel uncomfortable, but it should not be painful. You will have a light sedation or a general anaesthetic and the back of your throat is numbed with a local anaesthetic spray.

During the bronchoscopy, the doctor may take a tissue sample. Tissue samples may be taken by a biopsy or by "washing" or "brushing".

In washing, salt water is put through the bronchoscope which removes cells from the lung's lining and the water is sucked back out for testing. Another way uses a soft, brush-like tool put into the bronchoscope to get cells from the bronchi by brushing the airway.

An EBUS (endobronchial ultrasound) is a special type of bronchoscopy. The bronchoscope has a small ultrasound probe on the end. This can measure the size and position of a tumour or lymph nodes and helps the doctor taking a biopsy from any abnormal areas. It is only available in a few centres in New Zealand.

After a bronchoscopy, people often have a sore throat or cough up a small amount of blood. Tell your medical team if this happens. The sedation used for bronchoscopy (midazolam) can sometimes make it difficult to remember what happened during it, or even that you had one.


A surgeon uses a mediastinoscope to examine and sample the lymph nodes at the centre of your chest. A mediastinoscopy is done under general anaesthetic. A tube is put into a small cut in the front of your neck above the breast bone, and passed down the outside of your windpipe (trachea). The surgeon checks the area between the lungs (mediastinum) and removes some lymph nodes.

Often you will be home the same day, but you may need to stay the night in hospital. The scar on your neck is usually small.


Doctors only do a thoracotomy if other tests cannot give a diagnosis. Surgeons do this operation under general anaesthetic (you'll be asleep). They will take a sample (biopsy) of an abnormal area or remove all of the abnormal area.

The surgery can be done in two ways; either:

  • the surgeon makes some small cuts in your chest and inserts a surgical tool called a thoracoscope (a tube with a video camera) or
  • the surgeon opens the chest cavity through a larger cut on your back or side.

After surgery, you will probably stay in hospital for a few days while you recover.

Mutation testing

Each type of lung cancer has subtypes. Several lung cancer subtypes are grouped by changes or mutations to certain genes, such as adenocarcinoma.

The pathologist tests for these gene mutations that can provide information about treatment options so you can have the best outcome. A small number of people may have a cancer with a mutation that can be better treated with newer targeted drugs (usually tablets) rather than standard chemotherapy. For more information, see the section about targeted therapy and chemotherapy.

Further tests

You may have other tests such as blood and breathing tests, kidney tests and bone, brain or liver scans.

If your medical team suggests surgery to treat your cancer, you may need to have more tests to make sure your heart and lungs can cope with the operation. If you have any questions, please ask your doctors or nurse.

Key points: How lung cancer is diagnosed

  • Doctors use tests to diagnose lung cancer and help develop a treatment plan.
  • Tests—X-rays, CT scans or PET scans, and MRI—are used to make images of the inside of your body to see if you have a lump and if it has spread.
  • A piece of the cancer may need to be sampled (a biopsy) to determine which type it is. There are many different ways a biopsy can be taken.
  • Your cancer may also be tested for changes to specific genes (mutations) which will help cancer doctors offer the best treatment options for you.
  • When the results are all available, your doctor will talk to you about your prognosis (the expected outcome for you) or what may happen in your future. This will be based on the type of cancer and how fast it's growing and its stage.
  • You will probably see many doctors, nurses and health care professionals who will work together as a multidisciplinary team to diagnose and treat you. For more information, see "Multidisciplinary Care Team (MDT)".

Staging lung cancer

Your doctor will "stage" your cancer based on the diagnostic test results. Staging the cancer helps your medical team decide on the best treatment to offer you.

Staging is based on how much cancer is in the body and where it is. To decide on a stage, doctors need to know:

  • the size of the cancer in the lung
  • whether it's in other organs in the chest
  • if it has spread to lymph nodes (glands) in the chest or neck
  • if it has spread to other parts of the body.

The most common tests to stage lung cancer include X-rays, CT scans, PET scans, bone scans, MRI scans and, sometimes, more biopsies to test for cancer cells. Your doctor will work out the appropriate tests for you.

This table is a simplified version of how lung cancer is staged.

Non-small cell and small cell lung cancer

Stage 1

Only one lobe of the lung is affected.

Stage 2

The tumour has spread to nearby lymph nodes or the tumour has grown into the chest wall.

Stage 3A

The tumour has spread to lymph nodes in the centre of the chest (mediastinum).

Stage 3B

Tumours have spread more extensively to lymph nodes in the mediastinum or neck, or have become attached to major blood vessels or the trachea.

Stage 4

The cancer cells have spread to distant parts of the body, such as the bones or liver.


Key points: Staging lung cancer


  • Staging tells you the size of the cancer in your lungs and if it has spread to other parts of your body.
  • After studying your test results, your doctor will "stage" your cancer between 1 and 4.
  • Staging helps your doctor decide on the best treatment for your lung cancer.