Lung cancer is one of the most common forms of cancer in the UK, with over 40,000 new cases diagnosed each year in the UK alone.
Cancer that originates in the lungs is known as primary lung cancer, cancer that begins in another part of the body and subsequently spreads to the lungs is known as secondary lung cancer.
There are two main types of primary lung cancer, classified by the type of cells in which the cancer starts;
- Non-small-cell lung cancer (NSCLC) – the most common form, responsible for more than 80% of cases. This type of lung cancer can either be squamous cell carcinoma, adenocarcinoma or large-cell carcinoma
- Small-cell lung cancer (SCLC) – a less common form, usually spreading faster than non-small-cell lung cancer
Non-small-cell lung cancer usually spreads more slowly than small-cell lung cancer and reacts and responds differently to treatment. There are four stages to NSCLC, these are broken down as follows:
Can be divided into two sub-stages:
- Stage 1A – tumour is less than 3cm/1.2inches in size
- Stage 1B – tumour is 3-5cm/1.2-2 inches in size
In Stage 2A lung cancer:
- The tumour is 5-7cm
- The tumour is less than 5cm and cancerous cells have spread to nearby lymph nodes
In Stage 2B lung cancer:
- The tumour is larger than 7cm
- The tumour is 5-7cm and cancerous cells have spread to nearby lymph nodes
- The cancer has not spread to lymph nodes but has spread to surrounding muscles or tissue
- The cancer has spread to one of the main bronchus (airways)
- The cancer has caused the lung to collapse
- There are multiple small tumours in the lung
In Stage 3A lung cancer, the cancer has either spread to the lymph nodes in the middle of the chest or into the surrounding tissue. This can be:
- The covering of the lung (the pleura)
- The chest wall
- The middle of the chest
- Other lymph nodes near the affected lung
In Stage 3B lung cancer, the cancer has spread to either of the following:
- Lymph nodes on either side of the chest, above the collarbone
- Another important part of the body, such as the oesophagus, trachea, heart or into a main blood vessel
In Stage 4 the cancer has either spread to both lungs or to another part of the body, such as the bones, liver or brain, or the cancer has caused fluid-containing cancer cells to build up around the heart or lungs.
As previously mentioned small-cell lung cancer is less common, spreads quicker than non-small-cell lung cancer and when the cells are examined under a microscope they are smaller in size than the cells of the non-small-cell lung cancer.
There are only two stages to this form of cancer, they are:
- Limited disease – the cancer has not spread beyond the lung
- Extensive disease – the cancer has spread beyond the lung