Breathe.

This simple act happens anywhere from 15 to 25 times per minute without us even thinking about it.

Your lungs’ natural reflex sets in motion a complex chain of events that give your heart and brain the oxygen-rich blood they need to work and expel carbon dioxide, the waste gas produced by the body.

This process – called gas exchange – is vital to life.

Within our lungs are about 300 million tiny alveoli, or air sacs, surrounded by blood vessels. Oxygen is transferred through the linings of the alveoli into the surrounding blood vessels, carried away to the rest of the body.

But in the case of lung cancer, cells grow abnormally, multiplying in an out of control manner, eventually forming a mass called a tumour. If the tumour grows, it can destroy the body’s healthy tissue in the lungs and even spread to other areas.

Three different types of lung cancer can grow in the lining membrane of the airway, where people breathe in:

• Squamous cell cancer: the most common, it makes up 40 to 45 per cent of lung cancers.
• Large cell undifferentiated cancer: makes up five to 10 per cent of lung cancers.
• Small cell cancers: accounts for 15 to 20 per cent of lung cancers. Spreads rapidly, but chemotherapy provides encouraging results.

Other types form in the outlying areas of lung.

• Adenocarcinoma: occurs 20 to 25 per cent of the time, and can occur in non-smokers.
• Bronchioloalveolar carcinoma: makes up less than five per cent of lung cancers. This type grows in more outlying areas of the lung, and can be found in non-smokers.
• Other: rare types of cancers can be found in the lungs, making up less than five per cent of all lung cancers.