Smoking and lung cancer: What’s my risk?

Smoking is a lifestyle habit that has been linked to multiple diseases such as heart disease, stroke, and multiple types of cancer. According to the Singapore Cancer Society1 and the World Health Organization (WHO)2, smoking is associated with at least 6 million deaths worldwide every year. If you are a smoker or know someone who smokes, read on to find out more about how smoking is associated with lung cancer.

What is lung cancer?

Our respiratory system is made up of organs and tissues that help us to breathe, with the lungs being the main organ involved. The lungs are two spongy organs made up of the right and left lung and are where the exchange of gases occurs.
When air is breathed in, it goes into the lungs which consist of the bronchi, bronchioles, and alveoli. The exchange of gases (oxygen and carbon dioxide) occurs here between the alveoli and the blood, for the removal of carbon dioxide and the supply of fresh oxygen.

Cancer occurs when cells in the body grow exponentially and out of control. When this originates in the lungs, it is known as lung cancer.
There are two main types of lung cancer:

  • Non-small cell lung cancer (NSCLC): most common type of lung cancer and accounts for a large number of lung cancers. Develops from the epithelial cells (cells that line the organs) and includes adenosarcomas, large cell carcinoma, and squamous cell carcinoma.
  • Small cell lung cancer (SCLC): associated with smoking and spreads quickly and easily to other parts of the body.

The most damaging characteristic of cancer is its ability to spread or metastasize to other parts of the body, which results in high mortality rates.
There are 5 stages of lung cancer – the higher the stage, the bigger the tumour and more severe the cancer. By stage 4, the cancer has already spread to neighbouring lymph nodes or other organs such as the brain or stomach.

What are the symptoms of lung cancer?

Lung cancer does not usually cause symptoms when it is still in the early stages. If symptoms are showing, it means that the lung cancer is already in the advanced stages.
Symptoms may include:

  • Recurring and chronic cough
  • Coughing up blood
  • Chest pains
  • Breathlessness
  • Unintentional weight loss
  • Hoarseness
  • Headaches
  • Bone pain
  • Recurring lung infection
  • Loss of appetite

How is smoking associated with lung cancer?

Smoking has long been associated with lung cancer and that is because cigarettes contain 7000 toxic chemicals with at least 70 known to be cancer causing. When smoke is inhaled, these chemicals enter your lungs and damage the DNA or deoxyribonucleic acids of your lung cells. Initially, your body responds by healing the damage; however, as time progresses and your smoking increases, your body will no longer be able to heal the damage, resulting in the formation of cancer cells.

These toxic chemicals also weaken your immune system making you more susceptible to infections and also reducing your body’s ability to identify, fight, and kill cancer cells. This coupled with the damaged DNA of lung cells, will result in the exponential and out of control growth and spread of cancer cells.
Smoking has also been associated with other types of cancers and diseases such as:

How common is lung cancer in smokers?

According to the Centres for Disease Control and Prevention (CDC), individuals who smoke are 15-30 times more likely to get or die from lung cancer than individuals who do not smoke3. Your risk of lung cancer increases with each day and cigarette you smoke. Studies have shown that even smoking just one cigarette a day puts you at an increased risk of lung cancer and other medical conditions.
People who quit smoking reduce their risk of lung cancer; this is also true for individuals exposed to secondhand smoke. Removing yourself from smokey situations can reduce your risk of developing lung cancer.
Although smoking is the main cause of lung cancer, there are also other causes such as:

  • Secondhand smoke: living with a smoker or being in a long-term proximity of a smoker can increase your risk of lung cancer.
  • Radon gas: radon gas is odourless, colourless, and tasteless. It is the second leading cause of lung cancer after smoking. It is a naturally occurring radioactive gas that can enter people’s homes through cracks or gaps in the ground.
  • Asbestos and carcinogens: workplace exposure to these chemicals can increase your risk of lung cancer.
  • Radiation therapy: previous radiation therapy on your chest or to treat another type of cancer can increase your risk of lung cancer.

What is the rate of lung cancer in Singapore?

The National Cancer Centre Singapore (NCCS) reported that lung cancer is the 3rd most common cancer diagnosed in both males and females in Singapore4. It has the highest rate of mortality (death) in Singapore because they are usually only discovered when symptoms start to show which is when the cancer is already in the advanced stages.

How can I reduce my risk of lung cancer?

  • Quit smoking: the best and most effective way to reduce your risk of lung cancer, is to quit smoking or not start smoking in the first place.
  • Avoid secondhand smoke: ensure that your home and car is smoke-free to reduce your risk of developing lung cancer.
  • Screening: early detection can improve the curability of lung cancer, therefore if you are between the ages of 55 to 74 and have smoked 30 or more pack years, you are encouraged to go for a low dose computed tomography scan (CT-scan) used to screen for lung cancer.

In conclusion…

Smoking puts you at very high risk of lung cancer – not just yourself, but for your loved ones as well when they inhale your secondhand smoke.
If you are a smoker and want to screen or assess your risk for lung cancer, feel free to drop me a message and my friendly team will get in touch.


  1. Singapore Cancer Society. (2022). Live a smoke-free life: What you should know about smoking. Retrieved from Singapore Cancer Society:
  2. World Health Organization. (2022, May 24). Tobacco. Retrieved from World Health Organization:
  3. Centers for Disease Control and Prevention. (2022, October 25). Lung Cancer. Retrieved from Centers for Disease Control and Prevention:
  4. National Cancer Centre Singapore. (2022, March 8). Cancer Statistics. Retrieved from National Cancer Centre Singapore:
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