Lung cancer

Lung cancer

Lung cancer begins when abnormal cells grow and multiply in an uncontrolled way in one or both of the lungs. Cancer that starts in the lungs is known as primary lung cancer. It can spread to other parts of the body such as the lymph nodes, brain, adrenal glands, liver and bones.

When cancer starts in another part of the body and spreads to the lungs, it is called secondary or metastatic cancer in the lung.

The information here is about primary lung cancer only.

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The lungs

The lungs are the main organs for breathing, and are part of the respiratory system. As well as the lungs, the respiratory system includes the nose, mouth, trachea (windpipe), and airways (tubes) to each lung. There are large airways known as bronchi (singular: bronchus) and small airways called bronchioles.


The lungs look like two large, spongy cones. Each lung is made up of sections called lobes – the left lung has two lobes and the right lung has three.


The lungs rest on the diaphragm, which is a wide, thin muscle that helps with breathing.


The space between the two lungs is called the mediastinum. Several structures lie in this space, including:

  • the heart and large blood vessels
  • the trachea – the tube that carries air into the lungs
  • the oesophagus – the tube that carries food to the stomach
  • lymph nodes – small structures that collect and destroy bacteria and viruses.


The lungs are covered by two layers of a thin sheet of tissue called the pleura, which is about as thick as plastic cling wrap. The inner layer (the visceral layer) lines the lung surface, and the outer layer (the parietal layer) lines the chest wall and diaphragm. The layers are separated by a film of fluid that lets them slide over each other.

This helps the lungs move smoothly against the chest wall when you breathe. The pleural cavity is the potential space between the two layers, but there is no space between them when the lungs are healthy.

The respiratory system

 respiratory system lung

How breathing works

When you breathe in (inhale), air goes into the nose or mouth, down the trachea and into the bronchi and bronchioles. At the end of the bronchioles, tiny air sacs called alveoli pass oxygen  into the blood and collect the waste gas (carbon dioxide).

 When you breathe out (exhale), carbon dioxide is removed from the body and released back into the atmosphere.

The different types of lung cancer

There are two main types of primary lung cancer. These are classified according to the type of cells affected.

Types of lung cancer


non-small cell lung cancer (NSCLC)

NSCLC makes up about 85% of lung cancers. It may be classified as:

  • adenocarcinoma − begins in mucus-producing cells; more often found in outer part of the lungs
  • squamous cell carcinoma – begins in thin, flat cells; most often found in larger airways
  • large cell undifferentiated carcinoma − the cancer cells are not clearly squamous or adenocarcinoma

small cell lung cancer (SCLC)

SCLC makes up about 15% of lung cancers.  It tends to start in the middle of the lungs, and usually spreads more quickly than NSCLC.

Other types of cancer can also affect the lung area, but are not considered lung cancer. These include tumours that start in the space between the lungs (mediastinum) or in the chest wall.

Pleural mesothelioma is a cancer that affects the covering of the lung (the pleura). It is different to lung cancer and is usually caused by exposure to asbestos.

For more on this, see Pleural mesothelioma.

What causes lung cancer?

The causes of lung cancer are not fully understood, and some people develop lung cancer without having any known risk factors. The factors listed below are known to increase the risk of developing the disease. Having these risk factors does not mean you will develop lung cancer, but if you are concerned about your risk, talk to your doctor.

Tobacco smoking

In Australia, about 90% of lung cancer cases in males and 65% in females are estimated to be a result of tobacco smoking. The earlier a person starts smoking, the longer they smoke and the more cigarettes they smoke, the higher the risk of developing lung cancer. However, about one-fifth (21%) of people who are diagnosed with lung cancer have never been smokers.

Second-hand smoking 

Breathing in other people’s tobacco smoke (passive or second-hand smoke) can cause lung cancer. Living with a smoker increases a non-smoker’s risk by 20−30%.

Exposure to asbestos 

People who are exposed to asbestos are more likely to develop lung cancer or pleural mesothelioma. Although the use of asbestos in building materials has been banned across Australia since 2004, there is still asbestos in some older buildings and fences.

Exposure to other elements 

People exposed to radioactive gas (radon) in the workplace, such as uranium miners, have an increased risk of lung cancer. Contact with the processing of arsenic, cadmium, steel and nickel may also be a risk factor.

Family history 

You may be at a higher risk if a family member has been diagnosed with lung cancer.

Personal history 

Having another lung disease (e.g. lung fibrosis, chronic bronchitis, pulmonary tuberculosis, emphysema) or HIV infection may increase the risk of lung tumours.

Older age 

Lung cancer is most commonly diagnosed over the age of 60 years, though it can occur in younger people.

Who gets lung cancer?

Each year, about 11,500 Australians are diagnosed with lung cancer. The average age at diagnosis is 71. It is the fifth most common cancer in Australia and accounts for 9% of all cancers diagnosed. More men than women develop lung cancer. The risk of being diagnosed before the age of 85 is 1 in 13 for men and 1 in 21 for women.

Click on the icon below to download a PDF booklet on lung cancer.

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Apple devices

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Different ways to download an EPUB file to your Apple device:

  • email EPUB files to yourself and transfer the attachment to iBooks.
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To download an EPUB file to your Kobo from a Windows computer:

  • download and save the EPUB directly onto your desktop.
  • connect your Kobo to your computer using the USB cable and tap “Connect” on your eReader.
  • select “Open folder to view files” to view the contents of your Kobo.
  • navigate to where you have stored your EPUB file in “Finder”, in documents or downloads, and drag and drop it into the Kobo window. You can now disconnect your Kobo to read the eBook.

To download an EPUB to your Kobo from a Mac:

  • download and save the EPUB directly onto your desktop.
  • connect your Kobo to your computer using the USB cable and tap “Connect” on your eReader.
  • open your “Finder” application.
  • select “Kobo eReader” from the listed devices to view the contents of your Kobo.
  • navigate to where you have stored your EPUB file in “Finder”, probably in documents or downloads, and drag and drop it into the Kobo window. You can now disconnect your Kobo to read the eBook.

Turn on your Kobo and your EPUB will be located in “eBooks”, while a PDF will be located in “Documents”.
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Sony Reader

To download an EPUB file on your Sony Reader™:

  • ensure you have already installed the Reader™ Library for PC/Mac software
  • select the eBook you want from our website and click the link to download it.
  • connect the Reader™ to your computer.
  • open the Reader™ Library software and click “Library” in the left-hand pane and select the eBook to view it.

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Amazon Kindle 2nd Generation devices

EPUB files can’t be read on the Amazon Kindle™. However, like most eReaders, Kindle™ 2nd Generation devices are able to display PDFs. We recommend that you download the PDF version of this booklet if you would like to read it on a Kindle™.
To transfer a PDF to your Kindle™ via USB cable from your computer or Mac:

  • download the PDF directly onto your computer.
  • connect the USB cable to your computer’s USB port, and the micro USB end of the cable to your Kindle™. Note: the Kindle™ won’t be available as a reading device while it is connected to your computer until it has been disconnected.
  • open the Kindle™ drive and several folders will appear inside. The “Documents” folder is where you will need to copy or drag the PDF to.
  • safely eject your Kindle™ from your computer and unplug the USB cable. Your content will appear on the Home Screen.

Kindle also provides a Kindle Personal Documents Service that allows users to send documents as an attachment directly to your eReader. For more information on this service, visit
For more information on accessing a PDF on your Kindle™, visit, log in to your account and click on Personal Document Settings.
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Android and PC

You can also download and open eBooks on Android devices and PCs with appropriate apps or software installed. Suitable eReader apps for Android include Google Play Books, FBReader and Moon+ Reader. Suitable software for PCs include Calibre and Adobe Digital Editions.

This information was last reviewed in November 2018
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