Lung cancer is a growth of abnormal cells inside the lung. These cells grow in an uncontrolled way and clump together to form a cluster or growth, known as a tumour. If the abnormal cells begin growing in the lung, it is called primary lung cancer. When cancer spreads to the lungs from another place it is called secondary lung cancer.
Lung cancer is one of the most common cancers in the world. Many cases of lung cancer are strongly associated with smoking.
What are the main types of lung cancer?
There are two main types of primary lung cancer – each starts in different types of cells in the lungs.
- Non-small cell lung cancer: This is the most common type of lung cancer, and accounts for over 80 per cent of cases. It usually spreads more slowly than small cell lung cancer. There are several types of non-small cell lung cancer including squamous cell carcinoma, adenocarcinoma and large cell carcinoma.
- Small cell lung cancer: Not as common as non-small cell lung cancer, causing about 12–15 per cent of lung cancer cases. The cancer cells are smaller in size than non-small cell lung cancer cells. It almost always occurs in heavy smokers.
What are the symptoms of lung cancer?
Lung cancer can be hard to diagnose in the early stages because there are usually no symptoms to start with. Sometimes lung cancer is discovered by chance, such as when a chest X-ray is done for another reason.
Many people with lung cancer eventually develop symptoms including:
- A new cough that doesn’t go away
- A different type of cough to one a person may usually have
- Coughing up blood
- Hoarseness or wheezing
- Shortness of breath or increased breathlessness during exertion
- Chest and/or shoulder pain
- Weight loss without trying
- Loss of appetite
- Repeated lung infections
- Swelling of the face or neck.
If the lung cancer has already spread to other parts of the body, it may cause symptoms such as bone pain or headaches.
These symptoms can also be caused by other medical conditions so it’s important to discuss them with a doctor.
What causes lung cancer?
Smoking is the major cause of lung cancer. Tobacco smoke contains many toxic (poisonous) substances that damage the lining of the lungs and airways. Up to 90 per cent of cases of the disease are caused by smoking (cigarettes, pipes and cigars) or by prolonged exposure to second-hand tobacco smoke (passive smoking). However, it is not known why one smoker develops lung cancer while another does not.
Lung cancer can also occur in people who never smoked or have never been exposed to second-hand smoke. In these cases, it can be hard to work out what causes the disease. It may be linked to occupational exposure to asbestos. The greater the exposure to asbestos at work, the greater the risk of lung cancer. This risk is even greater among smokers. Other occupational exposures that have been associated with lung cancer include contact with the processing of steel, nickel, chromium, exposure to arsenic and coal gas, and exposure to radiation.
Who gets lung cancer in Australia?
Lung cancer is uncommon in younger people but the risk of developing lung cancer increases significantly after the age of 50. In Australia, the chances of a person developing lung cancer by their 85th birthday is one in 17.
In Australia, lung cancer is the fifth most common cancer. It is the leading cause of death due to cancer. More than 12,000 Australians are diagnosed with lung cancer each year, and over 7,000 people in Australia die from the disease each year.
The longer a person smokes and the more cigarettes they smoke, the higher the risk of developing lung cancer.
What are the risk factors for lung cancer in Australia?
Risk factors that increase the chance of getting lung cancer include:
- Smoking or a past history of smoking: especially cigarettes, but also pipes or cigars. The risk is greatest for people who began smoking early in life, people who are or used to be a heavy smoker and those who smoked for many years
- Passive smoking – exposure to second-hand smoke
- A personal or family history of lung cancer
- Exposure to asbestos
- Exposure to radon (a naturally occurring radioactive gas that can build up inside houses in some areas)
- Heavy exposure to other toxic substances in the workplace such as radioactive compounds (e.g. uranium), chromium compounds, silica, nickel, arsenic, tar, diesel exhaust fumes, paint
- Exposure to industrial air pollution
- Radiotherapy treatment to the chest
- History of certain lung diseases such as tuberculosis (TB), chronic obstructive pulmonary disease (COPD) and pulmonary fibrosis.
How is lung cancer diagnosed?
If lung cancer is suspected, the doctor will order several tests to check for cancerous cells or tumours in the lungs and airways. These may include:
- Chest X-ray: This may show an abnormal mass or growth
- CT scan, MRI or PET scan: These scans can reveal small lesions that may not be visible on X-ray
- Sputum test: In someone who is coughing up sputum (also called mucus or phlegm), the doctor will obtain a sample of sputum and send it to the laboratory to test for cancer cells
- Biopsy: A biopsy involves taking a small sample of tissue from the airways or lungs and sending it to the laboratory to check for cancer cells. This is often done using a special instrument called a bronchoscope. A bronchoscope is a thin, flexible tube that can be inserted into the mouth or nose and passed down the throat to examine the airways and lungs. The procedure is known as a bronchoscopy.
The doctor may also order tests and scans to see if the cancer has spread to other parts of the body.
Treatment for lung cancer
The type of lung cancer treatment depends on many factors, including:
- The type of cancer (e.g. small cell or non-small cell lung cancer)
- Where the cancer first began growing in the body (e.g. if it started in the lungs or spread to the lungs from elsewhere)
- What the cancer cells look like under a microscope
- What stage the cancer is (e.g. how advanced it is when diagnosed, whether the cancer cells have spread beyond the lung and, if so, how far they have spread)
- How bad the symptoms are
- A person’s overall general health.
Depending on the factors above, treatment may include:
- Surgery: Surgery may be done to remove the part of the lung affected by cancer. The amount of lung tissue removed depends on how much of the lung is affected by cancer. In some cases, a person may have an entire lung removed (called a pneumonectomy), or a large section (lobe) of the lung removed (called a lobectomy), or a small section of lung removed (called a wedge or segmental resection). The aim of surgery is to get rid of all the cancer cells if possible. Surgery offers the best hope of a cure for non-small cell cancer if it hasn’t spread to other parts of the body. Surgery is not often used in the treatment of small cell cancer.
- Chemotherapy: This is a course of anti-cancer medicine given to destroy cancer cells. Chemotherapy works by disrupting the growth of cancer cells. The medicine is often given intravenously (IV) through a vein or as tablets.
- Radiotherapy: This is a course of high energy rays, given to kill or shrink the cancer. The radiation may come from outside the body (external radiation) or from radioactive materials placed directly in or near the tumour (internal or implant radiation or brachytherapy). External radiation is most commonly used to treat lung cancer.
- Laser treatment: Lasers use high-intensity light to shrink or destroy tumours. This can help to control the growth of cancer cells and unblock airways obstructed by a tumour. While it does not cure the cancer, it can provide symptom relief.
- Targeted therapy (biologic drugs): Some newer drugs have been developed that specifically target some of the abnormalities found in cancer cells. Some of these therapies only work in people who have certain genetic mutations. Cancer cells can be tested in a laboratory to see if they are suitable for targeted therapy.
- Clinical trials: Some people may be able to take part in trials of new treatments for lung cancer. Cancer Australia has a website with current Australian cancer trials that are recruiting in Australia.
What questions should I ask about treatment?
People should discuss the available treatment options with their doctor so that together, they can decide what the most appropriate treatments are for their situation.
It is important to know whether the aim of treatment is to try to cure the cancer or to relieve symptoms. This decision is usually based on the cell type, where the cancer cells are located, and whether there has been any spread beyond the lung tissue itself. It is also important to ask about any risks and potential side effects of the proposed treatment so that you know what to expect.
What is the outcome for someone with lung cancer?
The outcome for someone with lung cancer depends on:
- the type of cancer they have;
- how far it has spread;
- the person’s overall health; and
- suitability for surgery.
The results of treatment are best when the cancer is detected and treated early. People who have surgery or early-stage lung cancer have the best chance of a cure.
The survival rate for someone with lung cancer that has spread outside the chest is lower. Unfortunately, because most small cell lung cancers have spread by the time they are diagnosed, survival rates are low.
The aim of treatment for incurable lung cancer is to relieve symptoms and maintain a good quality of life. This type of treatment is called palliative care.
Can lung cancer be prevented?
You can greatly reduce the chances of developing lung cancer by:
- Never smoking
- Stopping smoking if you currently smoke
- Trying to avoid or minimise exposure to second-hand smoke
- Avoiding asbestos exposure and exposure to other cancer-causing substances such as radon (a naturally occurring radioactive gas)
- Maintaining a healthy lifestyle: eat a healthy diet and do regular physical activity.