What Is Lung Cancer?

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Cancer,  according to the Centers for Disease Control and Prevention is described as the uncontrollable growth of cells in the body. Lung cancer is a cancer that starts in one of 3 places: the windpipe, lung tissue, or the bronchus (main airway) according to Cancer Research UK. If it starts in the lungs it is described as primary lung cancer. If it starts elsewhere in the body and spreads to your lungs then it is secondary lung cancer

Lung cancer is the leading cause of cancer-related deaths worldwide1 causing more deaths yearly than prostate or breast cancer. Keep reading to find out about what causes cancer and factors that increase therisk of developing lung cancer. By the end of this article, hopefully, most questions you have with regard to lung cancer will be answered. 

Types of lung cancer

Lung cancer can be categorised into two main groups: non-small cell lung cancer and small cell lung cancer

Non-small cell lung cancer

This is the more common type of lung cancer. It includes::

Small cell lung cancer

It is less common than non-small cell lung cancer but usually more aggressive in nature. It is more commonly found in people who are smokers or have a past history of smoking3

Causes of lung cancer

Smoking is the most common cause of lung cancer. It is reported to be responsible for about 80% of lung cancer cases.4 

Apart from smoking, there are other risk factors such as eposure to second-hand smoke and exposure to radon gasthat can increase thelikelihood of developing lung cancer. See FAQs to familiarise yourself with these risk factors. 

Signs and symptoms of lung cancer

Signs and symptoms usually do not appear in earlier stages of the disease. They usually appear when the disease has progressed into later stages. These signs and symptoms include:

  • Cough that won’t go away
  • Breathlessness
  • Coughing up blood
  • Losing weight inexplicably (without trying or suddenly)
  • Persistent chest pain

Management and treatment for lung cancer

When healthcare professionals are choosing an appropriate treatment method, they take several things into consideration. They consider the type of cancer (non-small cell or small cell lung cancer), the stage at which the cancer is at and your general health. Patients are assessed individually for what might work best for them as opposed to using a ‘one size fits all’ approach. 

Treatment of non small cell lung cancer

Treatment for non-small cell lung cancer depends on the stage of the cancer and may include any of the following:4

Small cell lung cancer

Treatment for this type of lung cancer is difficult because of its aggressive nature. Treatment with small cell lung cancer is usually therefore aimed at increasing the survival rate and trying to improve the patient’s quality of life by alleviating their symptoms.1 


How is lung cancer diagnosed?

Your GP will start by asking you about any symptoms you’ve been experiencing as well as taking your past medical history. After this, you may be asked to take a blood test to rule out other possible causes of your symptoms such as a chest infection. 

A chest X-ray is usually the first method used to check for lung cancer. However, if the chest x-ray cannot confirm or excludethe presence of lung cancer, you may be required to get a CT scan.5

How can I prevent lung cancer?

Most cases of lung cancer can be preventedor have their risk of occurring significantly reduced by avoiding smoking, or if you are a smoker, by quitting smoking. 

One of the biggest indications of the likelihood of developing lung cancer in smokers is how long a person has been smoking. The longer a person has been smoking, the more likely they are to develop lung cancer, therefore quitting reduces this risk.6 With that being said, although the risk is reduced once you stop smoking, it is not eliminated. Former smokers still are at risk of developing lung cancer; therefore, early detection is extremely important.7 

Other ways thatcould reduce therisk of developing lung cancer

  • Avoid second-hand smoke: Steer clear of areas where there is smoke 
  • Avoid carcinogens: Avoid exposure to toxic chemicals, especially if your job is in a field where you may be exposed to harmful chemicals. Make sure that you are taking the necessary precautions to protect yourself e.g. dressing appropriately with a mask, suit, and gloves in areas where you are at a high risk of exposure to these chemicals
  • Pursue and maintain a healthy lifestyle: Exercise regularly, eat a balanced diet that contains lots of fruits and vegetables, and try to avoid high intake of fried red-meat.6

What are the stages of lung cancer?

Identifying the stage of lung cancer is essential as it guides healthcare professionals on what treatment options may provide the patient with the best outcomes. Knowing what stage the cancer is at also gives the medical team an indication of the prognosis of the lung cancer (how the disease may progress).8

According to the National Cancer Institute, lung cancer is staged using the TNM system

  • T: Size and of location main tumour
  • N: Lymph nodes nearby that have cancer
  • M: Whether cancer has spread to other areas of the body (metastasised) 

Non-small cell lung cancer stages go from 0-IV 

  • Stage 0: tumour is still small, only in the top lining of lung or bronchus 
  • Stage I: cancer is still in thelung tissue, has not spread to lymph nodes or other body parts (divided into IA and IB)
  • Stage II: tumour is larger than stage I and has started to spread to nearby lymph nodes (IIA and IIB) 
  • Stage III: by this stage, cancer has usually spread to lymph nodes in the chest area between the two lungs (mediastinum) (IIIA, IIIB,IIIC)
  • Stage IV: most advanced stage, cancer has spread to other body parts such as your liver and bones (metastasised)  

Small cell lung cancer has 2 stages:

  • Limited: Cancer is found in just one lung and maybe in some lymph nodes. It has not spread to the other lung or body parts  
  • Extensive: It has spread to your other lung and other chest areas. It may have spread to other organs as well8

How common is lung cancer?

According to Cancer Research UK;

  • In their lifetime, 1 in 15 females and 1 in 13 males will be diagnosed with lung cancer in the UK
  • Lung cancer was responsible for 13% of new cancer cases in the UK between 2016 and 2018, this was equivalent to approximately 48 500 new cases of lung cancer every year between 2016 and 2018

Who are at risk of lung cancer?

The following factors put people at risk of developing lung cancer:

  1. Tobacco Smoking: This is the main cause of lung cancer. The risk of continuous smokers developing lung cancer is about 50x more than those who have never smoked.6
  2. Second-hand smoking: It is important to note that lung cancer does occur in people who have never smoked before. In fact, about 25% of lung cancer cases occur inpeople who have never smoked.7 Being exposed to second hand smoke can also increase your risk of developing lung cancer.
  3. Exposure to radon
  4. Genetics: Having a family history of lung cancer
  5. People with COPD (or other pre-existing lung diseases)7
  6. Occupational exposure: People working certain jobs where you are exposed to elements such asbestos, silica, and heavy metals  

While these factors increase the risk of lung cancer, lung cancer is usually seen in the older population (over 75).

When should I see a doctor?

If you have any of the symptoms mentioned in this article, in particular, if you are coughing up blood or have a cough that won’t go away then you should schedule an appointment with your GP. 


Lung cancer can be classifiedd as non-small cell lung cancer or small cell lung cancer. The type of cancer as well as the stage of cancer is useful to determine the appropriate treatment and management options. Smoking is the main cause of lung cancer. Other factors that put you at risk of developing lung cancer include exposure to radon and second-hand smoke. Early detection is key when treating lung cancer, therefore if you are experiencing any of the symptoms described in this article do not hesitate to contact your doctor. 


  1. Semenova EA, Nagel R, Berns A. Origins, genetic landscape, and emerging therapies of small cell lung cancer. Genes & Development [Internet]. 2015 Jul 15;29(14):1447–62. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4526731/
  2. Clark SB, Alsubait S. Non Small Cell Lung Cancer [Internet]. PubMed. Treasure Island (FL): StatPearls Publishing; 2020. Available from: https://www.ncbi.nlm.nih.gov/books/NBK562307/
  3. Rudin CM, Brambilla E, Faivre-Finn C, Sage J. Small-cell lung cancer. Nature Reviews Disease Primers [Internet]. 2021 Jan 14;7(1):1–20. Available from: https://www.nature.com/articles/s41572-020-00235-0
  4. Faraz Siddiqui, Siddiqui AH. Lung Cancer [Internet]. Nih.gov. StatPearls Publishing; 2019. Available from: https://www.ncbi.nlm.nih.gov/books/NBK482357/
  5. Latimer KM, Mott TF. Lung Cancer: Diagnosis, Treatment Principles, and Screening. American Family Physician [Internet]. 2015 Feb 15;91(4):250–6. Available from: https://www.aafp.org/pubs/afp/issues/2015/0215/p250.html
  6. Malhotra J, Malvezzi M, Negri E, La Vecchia C, Boffetta P. Risk factors for lung cancer worldwide. European Respiratory Journal [Internet]. 2016 May 12;48(3):889–902. Available from: https://erj.ersjournals.com/content/48/3/889
  7. Schabath MB, Cote ML. Cancer Progress and Priorities: Lung Cancer. Cancer Epidemiology and Prevention Biomarkers [Internet]. 2019 Oct 1;28(10):1563–79. Available from: https://cebp.aacrjournals.org/content/28/10/1563.figures-only
  8. Lemjabbar-Alaoui H, Hassan OU, Yang Y-W, Buchanan P. Lung cancer: Biology and treatment options. Biochimica et Biophysica Acta (BBA) - Reviews on Cancer [Internet]. 2015 Dec;1856(2):189–210. Available from: https://www.sciencedirect.com/science/article/pii/S0304419X15000669

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This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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