Staging of lung cancer
The stage of a cancer describes its size, position and whether it has spread beyond where it started in the body.
Knowing the extent of the cancer helps the doctors decide on the most appropriate treatment.
Generally, cancer is divided into four stages:
Stage 1 The cancer is small and localised.
Stages 2 or 3 The cancer has spread into surrounding areas.
Stage 4 The cancer has spread to other parts of the body.
If the cancer has spread to distant parts of the body, this is known as secondary or metastatic cancer. If the cancer comes back after initial treatment it’s known as recurrent cancer.
The current staging system is used for both small cell and non-small cell lung cancers. This aims to help doctors plan the best treatment for people with lung cancer. It can also help to give an idea of the likely outcome of treatment.
Staging small cell lung cancers
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Although the current staging system is for both non-small cell and small cell lung cancers, there is another system that has been used for many years, which you may hear your doctors refer to. This system divides small cell lung cancers into two stages:
Limited disease – the cancer cells can be seen only in one lung, in nearby lymph nodes, or in fluid around the lung (known as a pleural effusion).
Extensive disease – it’s clear that the cancer has spread outside the lung, within the chest area or to other parts of the body.
Small cell lung cancer often spreads outside the lung quite early on. Even if the doctor can’t see any evidence of the spread on your scans, it’s likely that some cancer cells will have broken away and travelled through the bloodstream or lymphatic system.
To be safe, small cell lung cancers are usually treated as though they have spread, whether any secondary cancer can be seen or not.
Staging non-small cell lung cancer
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The staging of non-small cell lung cancer is complicated. Here we describe a very simplified version. You can ask your specialist about the staging of your cancer.
You may want to look at the diagram of the lungs as you read through the stages.
The cancer is very localised and hasn’t spread to the lymph nodes. This stage is divided into two:
The cancer is no bigger than 3cm.
The cancer is over 3cm but no bigger than 5cm. It may affect nearby structures such as the main airway of the lung (bronchus) or the membrane covering the lung (pleura).Or, the lung has partially collapsed.
This stage is divided into two:
The cancer is no bigger than 7cm. It may affect nearby structures or the lung may have partially collapsed. The cancer may also affect nearby lymph nodes.
The cancer is over 5cm. The lung may have collapsed or there may be two or more tumours in the same lobe of the lung. It may have grown into nearby structures or spread to areas such as the chest wall or the muscle layer below the lungs (diaphragm). It may also have affected nearby lymph nodes.
This stage is also divided into two:
The cancer may be any size. It may affect nearby structures or it may have spread to areas such as the chest wall or heart. The lung may have collapsed. There may be two or more tumours in the same lobe of the lung or another tumour in a different lobe in the same lung. The cancer may have affected lymph nodes on the same side of the chest.
This stage is similar to 3A. The cancer may have affected the lymph nodes in the chest on the same side as the tumour or on the opposite side of the chest. Or the cancer may have affected the lymph nodes or at the top of the lungs or by the collarbone on either side of the chest.
The cancer has spread to the opposite lung. There is fluid around the lungs (malignant pleural effusion) or heart (malignant pericardial effusion). Or the cancer has spread to a distant part of the body such as the liver, bones or the brain.