Lung cancer

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Cancerous tumours of the lung

A cancerous tumour of the lung can grow into and destroy nearby tissue. It can also spread (metastasize) to other parts of the body. Cancerous tumours are also called malignant tumours.

There are 2 different types of lung cancer.

Small cell lung cancer

Small cell lung cancer is usually found in the main airways of the lung (bronchi) in the centre of the lungs. It is called small cell because the cancer cells look small when they are examined under a microscope. Even though the cells are small, they grow and spread very quickly to other parts of the body.

The main types of small cell lung cancer are small cell carcinoma and combined small cell carcinoma (mixed tumour with squamous or glandular cells).

Small cell lung cancer is the most aggressive type of lung cancer. In many cases it has already spread to other parts of the body when it is diagnosed. Small cell lung cancer is usually found in people who have smoked.

Non–small cell lung cancer

Non–small cell lung cancer is the most common type of cancerous tumour of the lung. About 80% to 85% of lung cancers are non–small cell lung cancer. Any lung cancer that is not a small cell lung cancer is considered to be a non–small cell lung cancer.

There are many different subtypes of non–small cell lung cancer that start in the different types of cells and tissues of the lung.


Adenocarcinoma is the most common type of non–small cell lung cancer. It starts in the lung cells that make mucus. Adenocarcinoma tumours are often found in the outer edges of the lungs.

While adenocarcinoma is usually found in people who smoke or used to smoke, it is the most common type found in people who never smoked. It is more often found in women and younger people.

There are many different subtypes of adenocarcinoma. They are given names based on what the cells look like when viewed with a microscope, the types of patterns that the cells are in, and whether or not the cells have mucus in them. Diagnosis, staging and treatment are similar for the different types of adenocarcinoma.

  • lepidic
  • acinar
  • papillary
  • micropapillary
  • solid
  • invasive mucinous (includes mixed mucinous, non-mucinous and colloid)
  • fetal
  • enteric
  • minimally invasive (includes non-mucinous and mucinous)
  • adenocarcinoma in situ (includes non-mucinous and mucinous)

Squamous cell carcinoma

Squamous cell carcinoma is the second most common type of non–small cell lung cancer. It starts in the flat cells that line the airways of the lungs (bronchi). Tumours are often found in the main airways of the lung. Squamous cell carcinoma is most often found in people who smoke or used to smoke.

There are different subtypes of squamous cell carcinoma:

  • keratinizing
  • non-keratinizing
  • basaloid
  • squamous cell carcinoma in situ

Superior sulcus (Pancoast) tumours

A superior sulcus tumour (Pancoast tumour) is found on the rounded upper part of the lung.  The tumour is named for its location in the lung. These tumours can be squamous cell carcinoma or adenocarcinoma. Because of where the cancer is growing, it is more likely to grow into the chest wall, rather than into the lung tissues. Superior sulcus tumours can grow into nerves, ribs and the bones of the spine.  

Large cell carcinoma

Large cell carcinoma was used to describe tumours with cells that looked very large when examined under a microscope. But a recent change in the way that lung cancer tumours are described means that this term is now only used for a very small number of lung cancer tumours.

Neuroendocrine lung tumours

Neuroendocrine tumours can start in the neuroendocrine cells in the lung. These cells receive messages (signals) from the nervous system and respond by making and releasing hormones, which are substances that control many body functions. Small cell lung cancer is the most common type of neuroendocrine lung tumour, but there are other types such as typical and atypical carcinoid tumours.

Find out more about neuroendocrine tumours of the lung.

Rare types of non–small cell lung tumours

The following are rare cancerous tumours of the lung:

  • adenosquamous carcinoma
  • sarcomatoid carcinoma
  • mucoepidermoid and adenoid cystic carcinomas
  • non-Hodgkin lymphoma
  • soft tissue sarcoma

Lung metastases

Lung metastases are cancerous tumours that have spread to the lung from another part of the body. The lung is one of the most common places where other cancers spread. Almost any kind of cancer can spread to the lung.

For example, breast cancer often spreads to the lung. This is called breast cancer with lung metastases. It would be treated like breast cancer, not like a cancer that started in the lung. 

Find out more about lung metastases.


A thick, slippery fluid made by glands in the mucous membranes. Mucus protects and lubricates the lining of some organs and body cavities, including the nose, mouth, lungs, vagina and gastrointestinal (GI) tract.


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