More about staging for lung cancer

The stage of a cancer means how big it is and whether it has spread. Knowing the stage is important because doctors decide on the treatment according to the stage of a cancer. The tests and scans used to diagnose lung cancer give some information about the stage. For most people, the tests described in the diagnosing lung cancer section are enough. But for some people it may not be possible to know the stage of the cancer until they have had an operation. 

All staging for cancer includes information about the size of the tumour, whether there is cancer in the lymph nodes, and whether the cancer has spread to anywhere else in the body.

There are different staging systems for cancer. You are most likely to be told the number stage of your cancer. This system divides lung cancers into one of 4 groups – stages 1 to 4. These take into account the size of the cancer and how far it has spread. 

The other staging system is the TNM staging system. This staging takes into account

• The size of the tumour (T)
• Whether cancer cells have spread into the lymph nodes close to the cancer (N)
• And whether the tumour has spread anywhere else in the body (M) 

If the cancer has spread it is called a secondary cancer or metastatic cancer. 

Doctors use the number system and TNM staging systems for both of the main types of lung cancer – non small cell and small cell lung cancer. These staging systems are very complex and can be difficult to understand. You can find out more about how the TNM staging system fits into the number staging system in our question and answer section.

Doctors sometimes use a simpler staging system for small cell lung cancer. They may describe it as limited disease or extensive disease. 

Limited disease means that the cancer is completely within the lung. 

Extensive disease means that the cancer has spread into lymph nodes outside the lung or into other body organs.

Lung cancers are divided into four stages:

Stage 1

The cancer is small and localised and there is no cancer in any lymph nodes. Stage 1 can be divided into 1A and 1B. 

Stage 1A means the tumour is small (up to 3cm). 

Stage 1B means the cancer is between 3 to 5cm – it has not spread into any lymph nodes or any other part of the body.

Stage 2

Stage 2 is divided into 2A and 2B.

Stage 2A means that the cancer is

• Between 5 and 7cm but there are no cancer cells in any lymph nodes OR
• 5cm or less and there are cancer cells in the lymph nodes close to the affected lung

Stage 2B means that the cancer is between 5 and 7cm and there are cancer cells in the lymph nodes close to the affected lung

Or stage 2B is when the cancer is

• Larger than 7cm but there are no cancer cells in any lymph nodes OR
• Not in any lymph nodes but has spread into one or more of the following areas – the chest wall, the muscle under the lung (diaphragm), the phrenic nerve, or the layers that cover the heart (mediastinal pleura and parietal pericardium) OR
• In the main airway (bronchus) close to where it divides to go into each lung OR
• Making part of the lung collapse OR
• Any size but there is more than one tumour in the same lobe of the lung

Stage 3

Stage 3 is divided into stages 3A and 3B. In this stage, the whole of the affected lung may have collapsed or may be inflamed due to the build up of mucus. Stage 3A can mean a number of different things. We have 3 diagrams to try to make it easier to understand.

Stage 3A can mean that the cancer is in the lymph nodes close to the lung and the cancer is bigger than 7cm.

OR stage 3A is when the cancer

• Has spread into one or more of the following areas – the chest wall, the muscle under the lung (diaphragm), or the layers that cover the heart (mediastinal pleura and parietal pericardium) OR
• Has spread into lymph nodes close to the main airway or in the centre of the chest on the same side as the affected lung

Or stage 3A is when the cancer is

• Any size but has grown into another major structure in your chest, such as the heart, the wind pipe (trachea), the food pipe (oesophagus), the nerve that goes to the voice box (larynx), a spinal bone, or a main blood vessel. There may also be cancer cells in lymph nodes close to the affected lung OR
• In more than one lobe of the same lung and may have spread into lymph nodes close to the affected lung

Stage 3B cancer can also mean a number of different things. It can mean that the cancer has spread into lymph nodes on the opposite side of the chest from the affected lung.

OR stage 3B is when the cancer is in the lymph nodes at the centre of the chest (mediastinum) and has spread into one or more of the following areas – the chest wall, the muscle under the lung (diaphragm), the layers that cover the heart (mediastinal pleura and parietal pericardium) or a major structure in your chest – such as the heart, the wind pipe (trachea), the food pipe (oesophagus) or a main blood vessel.

Stage 4

Stage 4 means that the cancer

• Is in both lungs OR
• Has spread to another part of your body – for example, the liver or bones OR
• Has caused a fluid collection around your lung or heart that contains cancer cells – (a malignant pleural effusion) or pericardial effusion

TNM staging takes into account

• The size of the tumour (T)
• Whether cancer cells have spread into the lymph nodes (N) close to the cancer
• And whether the cancer cells have spread anywhere else in the body, metastases (M)

From early 2010, a revised TNM staging system was introduced world wide. We describe the new system below.

Tumour (T)

The T stages for lung cancer are

• T1a – the tumour is contained within the lung and is smaller than 2cm across
• T1b – the tumour is contained within the lung and is between 2 and 3 cm across
• T2 – the tumour is between 3 and 7cm across or has grown into the largest airway (the main bronchus) more than 2cm below the part where it divides to go into each lung or the tumour has grown into the inner lining of the chest cavity (the visceral pleura) or the tumour has made part of the lung collapse. T2 tumours that are 5cm or smaller are classed as T2a and those larger than 5cm are T2b
• T3 – the tumour is larger than 7cm or has grown into one of the following structures – the chest wall, the central lining of the chest cavity (the mediastinal pleura), the muscle at the bottom of the chest cavity (the diaphragm), or the outer covering of the heart (the pericardium) or the tumour has made the whole lung collapse or there is more than one tumour nodule in the same lobe of the lung
• T4 – the tumour has grown into one of the following structures – the area between the lungs in the middle of the chest (the mediastinum), the heart, a major blood vessel, the wind pipe (trachea), the area where the main airway divides to go to each lung, the food pipe (oesophagus), a spinal bone, the nerve that controls the voice box, or there are tumour nodules in more than one lobe of the same lung

Nodes (N)

The N stages for lung cancer are

• N0 – there is no cancer in any lymph nodes
• N1 – there is cancer in the lymph nodes nearest the affected lung
• N2 – there is cancer in lymph nodes in the centre of the chest (mediastinum) but on the same side as the affected lung or there is cancer in lymph nodes just under where the windpipe branches off to each lung
• N3 – there is cancer in lymph nodes on the opposite side of the chest from the affected lung or in the lymph nodes above either collar bone or in the lymph nodes at the top of the lung

Metastases (M)

The M stages for lung cancer are

• M0 – there are no signs that the cancer has spread to another lobe of the lung or any other part of the body
• M1a – there are tumours in both lungs or fluid around the lung or heart that contains cancer cells – (a malignant pleural effusion) or pericardial effusion
• M1b – there are lung cancer cells in distant parts of the body, such as the liver or bones