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Diagnosis - Lung cancer

See a GP if you have symptoms of lung cancer, such as breathlessness or a persistent cough.

The GP will ask about your general health and your symptoms. They may examine you and ask you to breathe into a device called a spirometer, which measures how much air you breathe in and out.

You may be asked to have a blood test to rule out some of the possible causes of your symptoms, such as a chest infection.

Chest X-ray

A chest X-ray is usually the 1st test used to diagnose lung cancer. Most lung tumours appear on X-rays as a white-grey mass.

However, chest X-rays cannot give a definitive diagnosis because they often cannot distinguish between cancer and other conditions, such as a lung abscess (a collection of pus that forms in the lungs).

If a chest X-ray suggests you may have lung cancer, you should be referred to a specialist in chest conditions.

A specialist can arrange more tests to investigate whether you have lung cancer and, if you do, what type it is and how much it's spread.

CT scan

A CT scan is usually the next test you'll have after a chest X-ray. A CT scan uses X-rays and a computer to create detailed images of the inside of your body.

Before having a CT scan, you'll be given an injection containing a special dye called a contrast medium, which helps to improve the quality of the images.

The scan is painless and takes 10 to 30 minutes.

PET-CT scan

You may have a PET-CT scan may be done if the results of a CT scan show you have cancer.

The PET-CT scan (which stands for positron emission tomography-computerised tomography) can show where there are active cancer cells. This can help with diagnosis and choosing the best treatment.

Before having a PET-CT scan, you'll be injected with a slightly radioactive material. You'll be asked to lie down on a table, which slides into the PET scanner.

The scan is painless and takes 30 to 60 minutes.

Bronchoscopy and biopsy

If a CT scan shows there might be cancer in the central part of your chest, you may be offered a bronchoscopy.

A bronchoscopy is a procedure that allows a doctor to see the inside of your airways and remove a small sample of cells (biopsy).

During a bronchoscopy, a thin tube with a camera at the end, called a bronchoscope, is passed through your mouth or nose, down your throat and into your airways.

The procedure may be uncomfortable, so you'll be offered a sedative before it starts, to help you relax, and a local anaesthetic to make your throat numb. The procedure takes around 30 to 40 minutes.

A newer procedure is called an endobronchial ultrasound scan (EBUS), which combines a bronchoscopy with an ultrasound scan.

Like a bronchoscopy, an EBUS allows a doctor to see the inside of your airways. However, the ultrasound probe on the end of the camera also allows the doctor to locate the lymph nodes in the centre of the chest so they can take a biopsy from them.

The procedure takes around 90 minutes.

Lymph nodes are part of a network of vessels and glands that spread throughout the body and work as part of your immune system.

A biopsy from a lymph node can show if cancerous cells are growing there and what type they are.

Other types of biopsy

You may be offered a different type of biopsy. This may be a type of surgical biopsy, such as a thoracoscopy, a mediastinoscopy, or a biopsy done using a needle inserted through your skin (percutaneous).


A thoracoscopy is a procedure that allows a doctor to examine a particular area of your chest and take tissue and fluid samples.

You're likely to need a general anaesthetic before having a thoracoscopy.

Two or three small cuts will be made in your chest to pass a tube (similar to a bronchoscope) into your chest.

A doctor uses the tube to look inside your chest and take tissue samples. The samples are then sent to a laboratory for testing.

After a thoracoscopy, you may need to stay in hospital overnight while any fluid in your lungs is drained.


A mediastinoscopy allows a doctor to examine the area between your lungs at the centre of your chest (mediastinum).

For this test, you'll need to have a general anaesthetic and stay in hospital for a couple of days.

The doctor will make a small cut at the bottom of your neck so they can pass a thin tube into your chest. The tube has a camera at the end, which enables a doctor to see inside your chest.

They'll also be able to take samples of cells from your lymph nodes during the procedure. The lymph nodes are tested because they're usually the first place that lung cancer spreads to.

Percutaneous needle biopsy

During a percutaneous needle biopsy, a local anaesthetic is used to numb the skin. A doctor then uses a CT scanner or ultrasound scanner to guide a needle through your skin into your lung to the site of a suspected tumour.

The needle is used to remove a small amount of tissue from a suspected tumour so it can be tested at a laboratory.

Risks of biopsies

Like all medical procedures, a lung biopsy carries a small risk of complications, such as a pneumothorax. This is when air leaks out of the lung and into the space between your lungs and the chest wall.

This can put pressure on the lung, causing it to collapse.

The clinician doing the biopsy will be aware of the potential risks involved. They should explain all the risks in detail before you agree to have the procedure. They will monitor you to check for symptoms of a pneumothorax, such as sudden shortness of breath.

If a pneumothorax does happen, it can be treated using a needle or tube to remove the excess air, allowing the lung to expand normally again.


Once tests have been completed, it should be possible for doctors to know what stage your cancer is, what this means for your treatment and whether it's possible to completely cure the cancer.

Non-small-cell lung cancer staging

Clinicians use a staging system for lung cancer called TNM, where:

  • T describes the size of the tumour (cancerous tissue)
  • N describes the spread of the cancer into lymph nodes
  • M describes whether the cancer has spread to another area of the body such as the liver (metastasis)


There are 4 main stages for T:

T1 lung cancer means that the cancer is still inside the lung.
T1 is broken down into 3 sub-stages:

  • T1a – the tumour is no wider than 1cm
  • T1b – the tumour is between 1cm and 2cm wide
  • T1c – the tumour is between 2cm and 3cm wide

T2 is used to describe 3 possibilities:

  • the tumour is between 3cm and 5cm wide, or
  • the tumour has spread into the main airway or the inner lining of the chest wall, or
  • the lung has collapsed or is blocked due to inflammation

T3 is used to describe 3 possibilities:

  • the tumour is between 5cm and 7cm wide, or
  • there is more than 1 tumour in the lung lobe, or
  • the tumour has spread into the chest wall, the phrenic nerve (a nerve close to the lungs), or the outer layer of the heart (pericardium)

T4 is used to describe a range of possibilities including:

  • the tumour is wider than 7cm, or
  • the tumour has spread into both sections of the lung (each lung is made up of 2 sections, known as lobes), or
  • the tumour has spread into an area of the body near to the lung, such as the heart, the windpipe, the food pipe (oesophagus) or a major blood vessel


There are 3 main stages for N:

N1 is used to describe cancerous cells in the lymph nodes located inside the lung or in the area where the lungs connect to the airway (the hilum).

N2 is used to describe 2 possibilities:

  • there are cancerous cells in the lymph nodes located in the centre of the chest on the same side as the affected lung, or
  • there are cancerous cells in the lymph nodes underneath the windpipe

N3 is used to describe 3 possibilities:

  • there are cancerous cells in the lymph nodes located on the chest wall on the other side of the affected lung, or
  • there are cancerous cells in the lymph nodes above the collar bone, or
  • there are cancerous cells in the lymph nodes at the top of the lung


There are 2 main stages for M:

  • M0 – the cancer has not spread outside the lung to another part of the body
  • M1 – the cancer has spread outside the lung to another part of the body

Small-cell lung cancer

Small-cell lung cancer is less common than non-small-cell lung cancer. The cancerous cells are smaller in size than the cells that cause non-small-cell lung cancer.

Small-cell lung cancer only has 2 possible stages:

  • limited disease – where the cancer is only in 1 lung and may be in nearby lymph nodes
  • extensive disease – where the cancer has spread to the other lung, to lymph nodes that are further away, or to other parts of your body

Want to know more?

Lung cancer screening

There's currently no national screening programme for lung cancer in the UK. However, trials and studies are assessing the effectiveness of lung cancer screening, so this may change in the future.

Page last reviewed: 01 November 2022
Next review due: 01 November 2025