Lung cancer

Lung cancer is the abnormal, uncontrolled growth of lung cells. This is caused by changes to their genetic material. Different types of lung cancers arise from different cell types within the lung. The process by which this occurs is poorly understood.

Most lung cancer types are classified by their microscopic appearance. These include:

• Small cell lung cancer
• Non-small cell lung cancer: squamous cell carcinoma, adenocarcinoma and large cell carcinoma.

Other types of cancer can also occur in the lung. Some of these are rare types of cancer that arise from lung tissue.

Of lung cancers in Australia:

• 10% are small cell lung cancers.
• 60% are non-small cell lung cancer.
• 30% are rare types of lung cancer or cannot be definitively classified.

Cancer cells from other organs can also spread (metastasise) to the lung.

Mesothelioma is a type of cancer that starts in the lining of the chest and spreads into the lungs. Exposure to asbestos is strongly linked to mesothelioma. For more information about mesothelioma, please visit Cancer Council Victoria.

The treatment and outlook for lung cancer depends on the type of cancer, and how far the cancer cells have spread. Lung cancers may be:

• Contained within one part of a lung.
• Spread to several sites across the lungs.
• Spread (metastasised) to other parts of the body.

Most cases of lung cancer in Australia are detected at later, harder-to-treat stages.

Lung cancer occurs because of genetic changes in lung cells. These occur more frequently in people exposed to DNA-damaging agents such as tobacco smoke.

People who have smoked are 10 times more likely to develop lung cancer than non-smokers. Lung cancer is often associated with smoking (tobacco), however 1 in 3 women and 1 in 10 men diagnosed with lung cancer have no history of smoking. People who have never smoked tend to develop adenocarcinoma.

Specific cancer-promoting genetic changes have been discovered in adenocarcinomas in non-smokers. Understanding the genes that drive lung cancer growth and spread is allowing new treatments to be designed that can be matched to the genetic changes found in a patient’s lung cancer cells.

• Exposure to tobacco smoke or other forms of smoke, including smog or traffic fumes.
• Exposure to radiation such as the radioactive gas radon, or chest radiation to treat another cancer.
• Exposure to other cancer-causing (‘carcinogenic’) substances.
• Gender: amongst non-smokers, females are at higher risk of developing non-small cell lung cancer.
• Age: lung cancer rates increase with age.
• Lung inflammation and scarring, from other lung diseases.
• Family history: close relatives of a non-smoker with lung cancer are more likely to get the same disease.

Treatment for lung cancer depends on the type of lung cancer and how far the cancer cells have spread. Currently, most lung cancers are only discovered when they have spread beyond the lungs, which reduces the likelihood of treatment curing the disease.

Lung cancers that are small and confined to one section of a lung can often be successfully removed by surgery.

Lung cancers are often treated with:

• Chemotherapy and radiotherapy to kill rapidly growing cells
• Targeted therapies that match medicines to the proteins that are driving the cancer’s growth. For example, lung cancers with high levels of the EGFR protein can be successfully treated with medications that block EGFR function

For more information about how lung cancer is treated and patient support, please visit Cancer Council Victoria or the Lung Foundation Australia.

WEHI researchers are not able to provide specific medical advice specific to individuals. If you have lung cancer and wish to find out more information about clinical trials, please visit the Australian Cancer Trials or the Australian New Zealand Clinical Trials Registry, or consult your medical specialist.