What is Lung Cancer: Lung Cancer Symptoms, Causes and Stages

What is Lung Cancer?

Lung cancer occurs when abnormal cells in the lung grow in an uncontrolled way. The cancer often spreads (metastasises) in tumours to other parts of the body before it can be detected in the lungs. These tumours can affect how the lungs usually work, which is to supply oxygen to the body through the bloodstream and remove carbon dioxide from the body.

Although lung cancer can develop in any part of the lung, most lung cancers begin in the cells that line these air passages (bronchi) and the airway branches (alveoli or bronchioles) in the lung.

Lung cancer cells that remain within the lungs are classed as non-invasive lung cancer. When the tumour invades normal tissues in the lung, the tumour is considered to be malignant. The cells can also invade and multiply in nearby parts of the body, such as the chest wall or diaphragm, obtaining a new blood supply to continue tumour growth.

Lung cancer is one of the ten most common cancers in both men and women in Australia.

What causes lung cancer and who is at risk? 

There is not a direct cause related to development of lung cancer however there are certain types of risks and factors that can heighten the chance.

Factors that are associated with a higher risk of developing lung cancer include:

Lifestyle factors:

  • Current or former tobacco smoking – this is the greatest risk factor for lung cancer, and the risk is greatest for people who began smoking early in life, smoked for longer periods and smoked more often. Approximately 86% of females and 90% of males who are diagnosed with lung cancer have smoked in their lives. However around 12% of people diagnosed have not smoked at all. 

Environmental or occupational factors:

  • Exposure to secondhand smoke (passive smoking)
  • Occupational exposures, such as radon, asbestos, diesel exhaust and silica. Exposure to asbestos also increases the risk of developing mesothelioma, which starts in the lining surrounding the lungs (the pleura)
  • Exposure to air pollution

Personal factors:

  • Increasing age
  • Family history of lung cancer
  • A history of chronic lung disease, including chronic obstructive pulmonary disease and pulmonary fibrosis
  • A personal history of cancer, including lung cancer, head and neck cancer and bladder cancer

What are the key symptoms of lung cancer? 

Many conditions can cause similar symptoms as lung cancer. We recommend consulting with your doctor if you have or develop any of the below symptoms:

  • coughing up blood
  • a new or changed cough that doesn’t go away
  • chest pain and/or shoulder pain or discomfort – the pain may be worse with coughing or deep breathing
  • trouble breathing or shortness of breath
  • hoarse voice
  • weight loss
  • loss of appetite
  • chest infection that doesn’t go away
  • tiredness or weakness

It’s important to note that even if you have never smoked, you can develop lung cancer. Environmental and occupational factors are the second highest cause of lung cancer. This can include exposure to air pollution as well as occupational exposures of asbestos, radon, diesel exhaust and silica.

What are the stages of lung cancer?

Tests are conducted to help determine what stage of lung cancer a patient is at and if it has spread to other parts of the body. Knowing the stage of the disease helps determine which treatment is best.

Non–small cell lung cancer is divided into six stages, depending on whether the cancer has spread to other areas of the body:

  • Occult (hidden) stage: cancer cells are found in sputum or other fluids from the lung, but the cancer isn’t seen in other tests
  • Stage 0 (carcinoma in situ): the cancer is in the top layers of cells lining the air passages. It has not spread to lymph nodes or distant areas of the body
  • Stages I (divided into IA and IB), II (divided into IIA and IIB) and III (divided into IIIA and IIIB): these involve the cancer increasing in size, and spreading to nearby lymph nodes (stages II and III)
  • Stage IV: the cancer may have spread to the opposite lung, space around the lungs or heart, or other organs, such as bone, liver and brain

Small cell lung cancer is divided into two stages for the purposes of treatment:

  • Limited stage: the cancer is in only one side of the chest (possibly including lymph nodes) and can be treated with a single radiation field
  • Extensive stage: the cancer has spread widely throughout the lung, to the other lung, to lymph nodes on the other side of the chest or to distant organs

The staging system used for non–small cell lung cancer is increasingly being used for small cell lung cancer.

Tests to determine the stage of lung cancer can include:

  • imaging tests, including CT scans, PET scans, MRI, bone scans and ultrasound
  • endobronchial ultrasound (EBUS)
  • mediastinoscopy and mediastinotomy (rarely)
  • lymph node biopsy
  • bone marrow aspiration and biopsy (rarely used these days)
  • blood tests, to provide a complete blood count and for other laboratory tests

How is lung cancer treated? 

Treatment for lung cancer depends on the stage at the time of diagnosis. This includes the size of the tumour and if the tumour has spread in the lung, the type of lung cancer, cancer gene mutations and the overall health of the patient.

Treatment can include surgery to remove part or the whole lobe of the lung, the entire lung or part of the lung airway (bronchus). Radiation therapy and chemotherapy are also treatment options for patients.

An emerging body of research is indicating that knowing a tumour’s genomic profile could be more important for successful treatment than knowing its location or size. As each tumour’s genomic profile is unique, this approach is often referred to as personalised or precision medicine.

Treatment for lung cancer does depend on the stage of the cancer, the patient’s breathing capacity and general health. In most cases surgical removal of a tumour offers the best chance of a cure for patients who have early-stage lung cancer.

Types of Lung Cancer Surgery Include:

  • Lobectomy: Surgery where one lobe of a lung is removed (the right lung has 3 lobes, and the left lung has 2 lobes). A lobectomy is most commonly performed for a non-small cell carcinoma in which the tumour is confined to a single lobe. It is less invasive and conserves more lung function
  • Pneumonectomy: A procedure to remove an entire lung. There are two types of pneumonectomy procedures:
    • Standard Pneumonectomy: Either the right lung or the left lung is removed in its entirety
    • Extrapleural pneumonectomy: One of the lungs is entirely removed along with part of the diaphragm, the membrane lining the chest cavity and part of the membrane lining the heart
  • Wedge resection: Removes a small area of the lung that includes part of one or more lobes

Treatment for lung cancer can also depend on the type of lung cancer. Non-small cell carcinoma is best treated with surgery if possible. Small cell carcinoma is usually treated with chemotherapy. 

How you can help further lung cancer research

ACRF is committed to backing the brilliant ideas needed to find new ways to prevent, detect and treat all types of cancer, so that we can reach our vision of a world without this devastating disease.

ACRF awarded a $1 million grant in 2015 to The University of Queensland (UQ) Thoracic Research Centre and The Prince Charles Hospital, Brisbane to help establish The ACRF Centre for Lung Cancer Early Detection. The Centre focuses on the discovery and development of innovative methods for early-stage detection of lung cancer. 

ACRF awarded a $2 million grant in 2021 to help establish the The ACRF Lung Cancer Screening Centre of Excellence (LUSCE) at The University of Queensland Thoracic Research Centre. The world-first mobile lung cancer multiplatform research facility focused on early detection research for lung cancer – the leading cause of cancer deaths globally.

By donating to ACRF, you are helping to provide scientists with the tools, technology and infrastructure they need to accelerate cancer research. Click here to see donation options or to make a donation today.