National Cancer Centre Singapore
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Lung Cancer

Causes and Risks
Treatment Options
Frequently Asked Questions
National Cancer Centre Singapore
Contributed by National Cancer Centre Singapore


What is Lung Cancer?

The lungs are located in the chest and enable us to breathe. When we breathe in, air goes through our nose, down our windpipe (trachea), and into the lungs, where it spreads through tubes called bronchi. Oxygen from the air that we breathe can then pass into the blood and to the rest of the body to allow the body to function normally. 

Lung cancer refers to the uncontrolled growth of abnormal cells which come from the lungs, usually from the cells that line the bronchi. The abnormal cells do not carry out the function of normal lung cells. As these abnormal cells grow, they can get bigger and start to interfere with the normal functioning of the lung, they can pass from the original part of the lung to other parts of the body, such as the opposite lung, our lymph nodes, bones, liver etc.

How common is Lung Cancer?

Lung cancer is the number 2 killer in males and 3rd in females in Singapore. Between 2010 and 2014, there was an average of 1370 people in Singapore diagnosed with lung cancer yearly. 

Age of Onset

Most persons diagnosed with lung cancer are older than 40 years of age. However, the disease may begin before this age range.

Causes and Risks

Cigarette smoking is the main cause of lung cancer. The risk of lung cancer developing in a smoker is 15-25 times more than for a non-smoker. The risk of lung cancer is greater with increasing number of years of smoking and with higher number of cigarettes smoked per day. Pipe, cigar and marijuana smoking also increase the risk of lung cancer. Breathing in the smoke of others (called second hand smoke) can increase the risk of developing lung cancer by about 30%. The risk to children of smokers is not yet accurately quantified. 

Exposure to certain workplace chemicals such as asbestos, coal gas, chromium, nickel, arsenic, vinyl chloride, and mustard gas may also increase the risk of lung cancer.

Despite the strong association of smoking with lung cancer, it has also been recognised that more than one-quarter of lung cancer cases in Singapore occur in people who have never smoked, and who do not have prior smoke exposure.


Symptoms and Signs of Lung Cancer

Often, there may be no symptoms of lung cancer, particularly when it is at an early stage. However, common symptoms of lung cancer include:

1. A persistent cough that does not go away or gets worse
2. Blood in sputum
3. Increasing breathlessness
4. Pain in the chest that may be worsened with deep breathing or coughing
5. A change in the voice/ development of a persistent hoarse voice
6. Recurrent infection in the lungs
7. Loss of appetite and/ or unexplained weight loss and fatigue
8. A lump or swelling in the neck (which is due to cancer that has spread to the lymph nodes of the neck)
9. Bone pain, or headache or weakness of the arms or legs (which may be due to the lung cancer spreading to other parts of the body, such as the bones or the brain).


Diagnostic Tests

Any persistent cough or change in the nature of the cough, the appearance of blood-stained sputum, or unexplained breathlessness should prompt a person to seek medical advice. Often chest x-rays will then be performed and sputum may be sent for testing for cancer cells or infections, such as tuberculosis, which is not uncommon in Singapore. 

If the suspicion of cancer is high, or if the chest x-ray shows any abnormality, a special scan of the lungs, called a CT (computed tomography) scan may be performed to evaluate more accurately for presence of lung cancer. If this scan shows a suspicious mass, a biopsy may be recommended, where a small specimen from this mass is then obtained for examination under a microscope, to look for the presence of cancer cells.

In lung cancer, this biopsy can often be performed in a few different ways, such as passing a needle through the skin into the lung mass under x-ray guidance, or by performing a bronchoscopy examination, where a small tube is introduced through the mouth and into the lung. Small specimens from the suspicious lung mass can be removed for further examination. Alternatively, a biopsy sample may also be taken from the lymph nodes or other areas that the cancer has affected, such as the liver. 

After the diagnosis of lung cancer is made, further genetic tests may be performed on the cancer cells from the biopsy sample, which may help doctors decide which treatment is suitable for the lung cancer.

Lung function tests may be performed to determine how well the lungs are working and determine if it is safe to proceed with treatments such as surgery or radiotherapy to the lungs.

Once cancer is diagnosed, computerised tomography (CT) scans of the chest and liver may be performed to determine if the cancer has spread to other organs, such as the liver or adrenal gland, which is just above the kidneys on both sides. Occasionally, bone scans and CT scans of the brain are also required.

A lung function test, which involves blowing into a large cylinder, may be performed pre-operatively to determine the lung function prior to any surgery discussions.

Types of Lung Cancer

Types of Lung Cancer and Staging

The two main types of lung cancer are: 

• Non-small cell lung cancer (NSCLC) which is the most common type of lung cancer. 
• Small cell lung cancer (SCLC) makes up about 10-15% of all lung cancer cases.

Small cell lung cancer is more rapidly growing and spreads earlier to other organs as compared to non-small cell lung cancer. Non-small cell lung cancer generally grows slower than small cell lung cancer and tends to be confined to the lung for a longer period of time.

Once cancer is diagnosed, further scans of the bones, brain and rest of the body may be performed to determine if the cancer has spread to other organs. The results will be reviewed by the doctor to determine the final stage of the lung cancer.

Treatment Options

Treatment of Small Cell Lung Cancer

Chemotherapy is essential in the treatment of small cell lung cancer, due to its tendency to spread early to other organs, such as liver, bone and brain. If the cancer is still localised to one part of the lung and within the lymph nodes of the lung, radiotherapy to the lungs is administered together with chemotherapy. This combination of chemo-radiotherapy has been shown to have better results than just chemotherapy alone for patients with localised cancer. Surgery is usually not recommended for small cell lung cancer. The exact choice of chemotherapy medicine will depend on the person's general health and other prevalent medical problems. 

Treatment of Non-Small Cell Lung Cancer

Surgery, radiotherapy, chemotherapy and targeted therapy alone or in combination may be used to treat NSLC. In general, stage I and stage II cancer, where the cancer is localised to one part of the lung only, is usually treated with surgery to remove the lung cancer. Sometimes after surgery, further chemotherapy may be recommended to reduce the change of the cancer from returning.


For patients with stage III lung cancer, where the cancer may be large (>7cm), or have spread to the lymph nodes between both lungs, a combination of chemotherapy and radiotherapy to the lungs may be recommended.


For stage IV lung cancer, where the lung cancer cells have spread to other parts of the lungs and/ or body, further tests of the biopsy specimen to subtype the cancer further may help determine whether chemotherapy or targeted therapy with specific tablets will be more suitable. 

Prognosis of Lung Cancer

Prognosis means the probable outcome of an illness based upon all the relevant facts of the case. The results of patients' clinical examinations, x-ray investigations and biopsy reports are considered together in order to decide what the stage and progress of an individual case of lung cancer may be. From this, the appropriate course of treatment can be decided and put into action. The treatment strategy will vary from person to person.

The doctor looks for the following features:

  • Type of lung cancer (small cell or non-small cell)
  • The stage of the lung cancer, including whether any other parts of the body are affected
  • The size of the lung cancer
  • If surgery is done to remove the cancer, how many of the neighbouring lymph nodes which were involved and were all involved lymph nodes removed at surgery?
  • Patient's general condition, whether he has other medical problems that may affect the ability to treat his lung cancer effectively, for example, fitness for surgery


Avoid active and secondary tobacco smoke exposure. 

Frequently Asked Questions

1. I have been smoking for many years? Why should I stop smoking now?

Lung cancer takes years to develop. The risk increases with each year of smoking, and with each cigarette smoked per day. Stopping smoking will reduce the risk of cancer developing. Smoking also increases the risk of other diseases, such as chronic lung disease, heart disease, stroke and other cancers such as head and neck cancers. Stopping smoking will reduce the risk of lung cancer developing as well as reduce the likelihood of developing heart and lung problems.  Smoking can also harm your spouse and family members

2. How do I stop smoking? How do I stop a family member from smoking?

Smoking cessation clinics are available at many family practitioner's and polyclinics. Avail yourselves to any of these clinics. Giving a family member support will also help him or her to stop smoking. The Quit Programme has a self-help booklet that will also assist you.

Cancer Resources on the Internet

National Cancer Institute
Cancer Therapies
American Cancer Society
National Centre for Biotechnology Information (NCBI)
American Cancer Society
American Lung Association
Lung Cancer Resources Library
Cancer Information Service (National Cancer Institute, USA) 

Click here for English publication on Lung Cancer

Click here for Chinese publication on Lung Cancer

For further enquiries on lung cancer, please call the Cancer Helpline at (65) 6225 5655 or email to