What is lung cancer?
Lung cancer begins when abnormal cells grow and multiply in an uncontrolled way in one or both of the lungs. Cancer that starts in the lungs is known as primary lung cancer. It can spread to other parts of the body such as the lymph nodes, brain, adrenal glands, liver and bones.
When cancer starts in another part of the body and spreads to the lungs, it is called secondary or metastatic cancer in the lung. This information is about primary lung cancer only.
The lungs
The lungs are the main organs for breathing, and are part of the respiratory system. As well as the lungs, the respiratory system includes the nose, mouth, trachea (windpipe), and airways (tubes) to each lung. There are large airways known as bronchi (singular: bronchus) and small airways called bronchioles.
Lobes
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.
Diaphragm
The lungs rest on the diaphragm, which is a wide, thin muscle that helps with breathing.
Mediastinum
The space between the two lungs is called the mediastinum. Several structures lie in this space, including:
- the heart and large blood vessels
- the trachea – the tube that carries air into the lungs
- the oesophagus – the tube that carries food to the stomach
- lymph nodes – small structures that collect and destroy bacteria and viruses.
Pleura
The lungs are covered by two layers of a thin sheet of tissue called the pleura, which is about as thick as plastic cling wrap. The inner layer (the visceral layer) lines the lung surface, and the outer layer (the parietal layer) lines the chest wall and diaphragm. The layers are separated by a film of fluid that lets them slide over each other. This helps the lungs move smoothly against the chest wall when you breathe. The pleural cavity is the potential space between the two layers, but there is no space between them when the lungs are healthy.
How breathing works
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). When you breathe out (exhale), carbon dioxide is removed from the body and released back into the atmosphere.
What are the different types?
There are two main types of primary lung cancer. These are classified according to the type of cells affected.
Types of lung cancer
Non-small cell lung cancer (NSCLC)
NSCLC makes up about 85% of lung cancers. It may be classified as:
- adenocarcinoma – begins in mucus-producing cells; more often found in outer part of the lungs
- squamous cell carcinoma – begins in thin, flat cells; most often found in larger airways
- large cell undifferentiated carcinoma – the cancer cells are not clearly squamous or adenocarcinoma
Small cell lung cancer (SCLC)
SCLC makes up about 15% of lung cancers. It tends to start in the middle of the lungs, and usually spreads more quickly than NSCLC.
Other types of cancer can also affect the lung area, but are not considered lung cancer. These include tumours that start in the space between the lungs (mediastinum) or in the chest wall.
Pleural mesothelioma is a cancer that affects the covering of the lung (the pleura). It is different to lung cancer and is usually caused by exposure to asbestos. See Understanding Mesothelioma.
What are the risk factors?
The causes of lung cancer are not fully understood, and some people develop lung cancer without having any known risk factors. The factors listed below are known to increase the risk of developing the disease. Having these risk factors does not mean you will develop lung cancer, but if you are concerned about your risk, talk to your doctor.
Tobacco smoking
Aabout 90% of lung cancer cases in males and 65% in females are estimated to be a result of tobacco smoking. The earlier a person starts smoking, the longer they smoke and the more cigarettes they smoke, the higher the risk of developing lung cancer. However, about one-fifth (21%) of people who are diagnosed with lung cancer have never been smokers. 2
Second-hand smoking
Breathing in other people’s tobacco smoke (passive or second-hand smoke) can cause lung cancer. Living with a smoker increases a nonsmoker’s risk by 20-30%. 3
Exposure to asbestos
People who are exposed to asbestos are more likely to develop lung cancer or pleural mesothelioma (see above). Although the use of asbestos in building materials has been banned across Australia since 2004, there is still asbestos in some older buildings and fences.
Exposure to other elements
People exposed to radioactive gas (radon) in the workplace, such as uranium miners, have an increased risk of lung cancer. Contact with the processing of arsenic, cadmium, steel and nickel may also be a risk factor.
Family history
You may be at a higher risk if a family member has been diagnosed with lung cancer.
Personal history
Having another lung disease (e.g. lung fibrosis, chronic bronchitis, pulmonary tuberculosis, emphysema) or HIV infection may increase the risk of lung tumours.
Older age
Lung cancer is most commonly diagnosed over the age of 60 years, though it can occur in younger people.
What are the symptoms?
The main symptoms of lung cancer are:
- a persistent new cough or a change in an ongoing cough
- breathlessness
- chest and/or shoulder pain
- repeated bouts of pneumonia or bronchitis
- coughing or spitting up blood.
A person diagnosed with lung cancer may also have experienced symptoms such as fatigue, weight loss, hoarse voice, wheezing, difficulty swallowing, abdominal or joint pain, and enlarged fingertips (finger clubbing).
Having any one of these symptoms does not necessarily mean that you have lung cancer. Some of these symptoms may be caused by other conditions or from the side effects of smoking. However, if you have symptoms, see your doctor without delay.
Lung cancer symptoms can be vague and the disease is often discovered when it has spread to other parts of the body. Sometimes, there are no symptoms and the cancer is found during routine tests (often an x-ray or CT scan) for other conditions.
Which health professionals will I see?
Your general practitioner (GP) will organise the first tests to assess your symptoms. If these tests do not rule out cancer, you will usually be referred to a respiratory physician, who will arrange further tests. If lung cancer is diagnosed, the specialist will consider treatment options. Often these will be discussed with other health professionals at what is known as a multidisciplinary team (MDT) meeting. During and after treatment, you will see a range of health professionals who specialise in different aspects of your care. The health professionals you see will depend on whether the lung cancer has spread.
| Health professional | Role |
|---|---|
| GP | assists you with treatment decisions and works in partnership with your specialists in providing ongoing care |
| respiratory (thoracic) physician* | diagnoses diseases of the lungs, including cancer, and recommends initial treatment options |
| thoracic (chest) surgeon* | diagnoses and performs surgery for cancer and other diseases of the lungs and chest (thorax) |
| radiation oncologist* | treats cancer by prescribing and overseeing a course of radiation therapy |
| radiation therapist | plans and delivers radiation therapy |
| medical oncologist* | treats cancer with drug therapies such as chemotherapy, targeted therapy and immunotherapy (systemic treatment) |
| cancer care coordinator or lung cancer nurse coordinator |
coordinates care, liaises with MDT and supports you and your family throughout treatment; care may also be coordinated by a clinical nurse consultant (CNC) or clinical nurse specialist (CNS) |
| nurse | administers chemotherapy and other drugs and provides care, information and support throughout treatment |
| dietitian | recommends an eating plan to follow while you are in treatment and recovery |
| speech pathologist | helps with communication and swallowing after treatment |
| social worker | links you to support services and helps with emotional, practical or financial problems |
| physiotherapist, occupational therapist | assist with physical and practical issues, including restoring movement and mobility after treatment and recommending aids and equipment |
| counsellor, psychologist | help you manage your emotional response to diagnosis and treatment |
| palliative care specialist* and nurses | work closely with the GP and cancer specialists to help control symptoms and maintain your quality of life |
*Specialist doctor