Types of lung cancer

There are two main types of primary lung cancer, which behave and respond to treatment differently. They are:

  • small cell lung cancer (SCLC)
  • non-small cell lung cancer (NSCLC).

About 15% of lung cancers (less than 1 in 5) are small cell; the rest are non-small cell.

The ratio of small cell lung cancer to non-small cell lung cancer
The ratio of small cell lung cancer to non-small cell lung cancer

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Small cell lung cancer

Small cell lung cancer is called this because when the cancer cells are looked at under a microscope they are very small. It’s sometimes called oat cell cancer.

Small cell lung cancer is usually caused by smoking, and it’s rare for someone who has never smoked to develop this type of lung cancer. Small cell lung cancer is often fast-growing and can spread quickly.

Non-small cell lung cancer

There are three main types of non-small cell lung cancer. Sometimes it’s not possible to tell which type someone has. This is because when the cells are looked at under a microscope, they are not developed enough or the biopsy doesn’t contain enough cells to diagnose the different types of NSCLC.

  • Squamous cell carcinoma – This is the most common type of lung cancer. It develops in the cells that line the airways. This type of lung cancer is often caused by smoking.
  • Adenocarcinoma – This develops from the cells that produce mucus in the lining of the airways. This type of cancer is becoming more common.
  • Large cell carcinoma – This gets its name from the large, rounded cells that are seen when they are examined under a microscope. It’s sometimes known as undifferentiated carcinoma.


A less common type of cancer that can affect the covering of the lungs (the pleura) is called mesothelioma. This is a cancer of the membrane that covers the surface of the lungs and lines the inside of the chest. It often occurs in people who have been exposed to asbestos.

Rarer types of lung cancer

A rare type of cancer called a carcinoid tumour can sometimes develop in the lungs. Carcinoid tumours are a type of neuroendocrine cancer. The neuroendocrine system is a network of glands that produce hormones, which helps the different organs of the body to function. Rarer types of cancer, such as soft tissue sarcomas, can also develop in the lungs.

Back to Lung cancer

Cancer and cell types

Cancers are grouped into types. Types of cancer often behave and respond to treatments in different ways.

How it is treated

There are five main types of cancer treatment. You may receive one, or a combination of treatments, depending on your cancer type.

What is cancer?

There are more than 200 different kinds of cancer, each with its own name and treatment.

Why do cancers come back?

Sometimes, tiny cancer cells are left behind after cancer treatment. These can divide to form a new tumour.