The number stages of lung cancer

• A quick guide to what's on this page
• What staging is
• How lung cancer is staged
• What does each stage mean
• Pleural effusion

The stage of a cancer tells the doctor how far a cancer has spread. The tests and scans you have to diagnose your cancer will give some information about the stage. But it may not be possible to be completely sure until you have had an operation. In most cases however the tests described in the diagnosing lung cancer section are enough for your doctor to tell the stage. It is important because treatment is often decided according to the stage of a cancer.

All staging for cancer includes information on the size of the tumour, whether there is cancer in the lymph nodes and whether the cancer has spread 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 is a system that divides lung cancers into one of 4 groups, stages 1 to 4, depending on how far the cancer has spread. Your doctor may also describe your lung cancer as limited disease (small cancers contained within the lung) or extensive disease (cancer that has spread into the lymph nodes outside the lung or other organs).

The number system uses information from the TNM staging system. This is quite detailed and can tell the doctor the size of the primary cancer, whether it has spread to lymph nodes and whether it has spread anywhere else in the body. There is more about the TNM stages of lung cancer in this section of CancerHelp UK.

Lung cancer can be divided into four stages:

Stage 1

This means 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 stages 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

• Larger than 7cm but there are no cancer cells in any lymph nodes OR
• Between 5 and 7cm and there are cancer cells in the lymph nodes close to the affected lung 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 means that the cancer is

• In the lymph nodes close to the lung and the cancer is bigger than 7cm or 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
• Any size but has spread into lymph nodes close to the heart and main airway on the same side of the chest as the affected lung OR
• Any size but has grown into another major structure in your chest, which could be the heart, the windpipe (trachea), the food pipe (oesophagus), the nerve that goes to the voicebox, 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 means that the cancer is

• Any size and has spread into lymph nodes on the opposite side of the chest OR
• 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 (which could be the heart, the windpipe, the foodpipe or a main blood vessel).

 Stage 4 

This 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).

A pleural effusion is fluid between the membranes covering the outside of the lungs - the pleura. The fluid takes up space and makes it impossible for the lung to expand fully when you breathe. If there is a lot of fluid, it can make you very breathless.

The fluid has to be checked for cancer cells. If it contains cancer cells, it is called a malignant pleural effusion and will mean that you have a stage 4 cancer. Occasionally, someone with lung cancer has fluid around the lung but the fluid doesn't contain cancer cells. If there are no cancer cells, it doesn't count towards your lung cancer stage.

Your doctor will decide which stage you are by taking a number of different factors into account and pleural effusion is just one of these.