Lung cancer

Wednesday 30 June, 2010

Reviewed: Dr Nick Pavlakis, Medical Oncologist, Royal North Shore Hospital; Jocelyn McLean RN, MN (Res), Case Manager for Thoracic Surgery, Sydney South Western Area Health Service; Eileen Ryan, Consumer.

On this page: The lungs | What is lung cancer? | What are the different types? | How common is lung cancer?

The lungs 

The lungs are the main organs in the body's system for breathing, called the respiratory system. The respiratory system also includes the nose, mouth, windpipe (trachea) and airways to each lung. The airways to each lung are called large airways (bronchi) and small airways (bronchioles).

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). Carbon dioxide is released back into the atmosphere - and removed from the body - as you breathe out (exhale).

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.

A number of structures lie between the lungs (a space called the mediastinum), including:

  • the heart and large blood vessels
  • the trachea
  • the tube that carries food from mouth to stomach (oesophagus)
  • lymph glands (also known as lymph nodes).

The lungs are covered by a thin sheet of tissue called the pleura, which is about the thickness of plastic cling wrap. Its inner layer (the visceral layer) is attached to the lungs and its outer layer (the parietal layer) lines the chest wall and diaphragm. Between the two layers is the pleural cavity, which normally contains a thin film of fluid. This fluid allows the two layers of pleura to slide against each other so your lungs can move smoothly against the chest wall as you breathe.

 

The lungs

What is lung cancer?

Lung cancer is a malignant tumour in the tissue of one or both of the lungs.

Some people have primary cancer that started in the lungs. Others have cancer that started somewhere else in the body and spread to the lungs (secondary cancer or metastasis).

What are the different types? 

There are several types of lung cancer, which are classified according to the type of cell affected.

Non-small cell lung cancer (NSCLC)

Makes up 75-80% of lung cancers. It mainly affects the cells that line the tubes into the lungs (bronchi) and smaller airways. NSCLC is classified as:

Small cell lung cancer (SCLC)

Makes up 15-20% of lung cancers. SCLC tends to start in the middle of the lungs, and it usually spreads early. Cancers are named for the way the cells appear when viewed under a microscope. Types include:

  • small cell carcinoma (also known as oat cell cancer)
  • mixed small cell/large cell carcinoma
  • combined small cell carcinoma.  

Mesothelioma

A rare type of cancer that affects the protective membrane around the body's internal organs (the mesothelium). Mesothelioma usually affects the pleural membranes around the lungs, but it can also occur in the lining of the abdomen or around the heart.

Mesothelioma is almost always caused by exposure to asbestos, a mineral used in some building materials. In most cases, the development of mesothelioma occurs 25-50 years after asbestos exposure.

How common is lung cancer?

About 9,200 people (65% males, 35% females) are diagnosed with lung cancer in Australia each year. It is the fifth most common cancer in Australia. Lung cancer is most commonly diagnosed in people 65-79 years old.

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