This information was reviewed by:
Gavin Wright, Chair of the VCOG Lung Committee & Thoracic Surgeon, St Vincent’s Health.
Use the links above or text below to learn more about lung cancer, or download a pdf of our latest lung cancer booklet.
The chest cavity (thorax) is the area enclosed by the ribs, from below the neck and shoulders. The lower part is the diaphragm: a wide, thin dome of muscle a little above the waist. Below the diaphragm is the abdomen.
Most of the chest cavity is filled with the two large, spongy lungs. The lungs are roughly cone-shaped, and are made up of sections or lobes. The left lung has two lobes and the right lung has three.
When we breathe in, air is drawn through the nose or mouth into the throat and down the windpipe into the chest. The windpipe branches into two bronchi, one going to each lung. Inside the lungs, the bronchi branch many times, like a tree, to form smaller bronchi and then thousands of tiny tubes (bronchioles). Each bronchiole ends up at tiny, bubble-like air sacs. It is these air sacs (alveoli) that make the lungs spongy.
Blood flows between the thin walls of nearby air sacs. This allows oxygen to move from the air into the blood, and carbon dioxide (a waste product from the body) to move from the blood to the air, to be breathed out.
Two layers of thin membrane surround the lungs. This is called the pleura. The inner layer is attached to the lungs and the outer layer lines the chest wall and diaphragm. Between the two layers is the pleural cavity. This cavity is virtually empty. The two layers of pleura slide against each other, and they are moist and smooth so that your lungs can move smoothly against the chest wall as you breathe.
Lung cancer is cancer of some of the cells in part of your lung. It usually begins in the lining of the airway. A cancer that starts in cells lining an organ is called a carcinoma.
There are different types of lung cancer. Lung cancers are classified according to the main type of cell affected. There are two main types: small cell carcinomas and non-small cell carcinomas.
Small cell carcinomas are also called oat cell carcinomas because of the shape of the cell. They account for around 15% of lung cancers. This type of lung cancer is strongly linked with cigarette smoking. Unfortunately, it spreads early and causes few early symptoms, so it has often already spread at the time of diagnosis.
Non-small cell carcinomas include squamous cell carcinoma, adenocarcinoma, large cell carcinoma and bronchiolo-alveolar cell carcinoma.
Squamous cell carcinomas usually affect the cells that line the main bronchi. Adenocarcinomas and bronchiolo-alveolar cell carcinomas usually develop in the edge of the lung in the alveoli.
As these cancers grow they can spread into the chest wall and nearby lymph nodes. Squamous cell carcinoma has a lower rate of spread than other types of lung cancer and is generally found earlier, so there is a slightly better prognosis following treatment.
As with many cancers, we do not know the cause in all cases.
Up to 90% of lung cancers are caused by smoking. Lung cancer occurs most often in adults between the ages of forty and seventy who have smoked cigarettes for at least twenty years. They are also likely to have started smoking as teenagers.
Passive smoking (breathing in someone else's smoke) can cause lung cancer and other disease in adults, as well as causing illness in children and babies.
Also linked to lung cancer are contact with asbestos, and steel, nickel, chrome and coal gas processing. Exposure to radiation increases the risk of all cancers, including lung cancer. Miners of uranium, fluorspar and haematite may be exposed to radiation by breathing air contaminated with radon gas.
more than 2,300 Victorians are diagnosed with lung cancer each year. Lung cancer is the most common cause of death from cancer in Australian men and the second most common for women.
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