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According to the Singapore Cancer Registry from 2018 to 2022, approximately 9,000 cases of lung cancer were diagnosed in Singapore.

It (lung cancer) is the third* most common cancer affecting men and women in Singapore. In fact, it is the leading cause of cancer death in men and third leading cause of cancer death in women.

"Lung cancer occurs when there is an uncontrolled growth of abnormal cells in the lung which can interfere with normal lung function. The abnormal cells can pass from the original part of the lung to other parts of the body, such as the opposite lung, lymph nodes, bones, liver and more," explained Associate Professor Daniel Tan, Senior Consultant from the Division of Medical Oncology at National Cancer Centre Singapore (NCCS), a member of the SingHealth group. 

But can lung cancer be prevented and are there early signs to look out for? Read on to find out.

Lung cancer: How to prevent

As smoking is one of the main causes of lung cancer, the best way to minimise the risk of developing lung cancer is to avoid smoking. There are several ways to do this: 

• Primary prevention: If you have never smoked (this includes e-cigarettes/vapes), don’t start! 

• Secondary prevention: If you are a smoker, stop smoking.
  Stopping smoking at any age can help to reduce the risk of developing lung cancer. 
  For non-smokers, try your best to avoid exposure to second-hand smoke (from others around you who may smoke). 

• Go for screening: If you are aged between 55 to 74 and have smoked 30 or more pack years* and are continuing to smoke or quit less than 15 years ago, you can consider undergoing a low dose CT scan to screen for lung cancer. 

It is also recommended that you eat a diet rich in fruits and vegetables and to exercise regularly.

* According to the Singapore Cancer Registry Annual Report 2022.

* Pack years are calculated by multiplying the number of cigarette packs smoked daily by the number of years smoking. 

Symptoms of lung cancer

Lung cancer usually doesn’t have any symptoms in the early stages. At an advanced stage, patients may experience the following symptoms:

• A persistent cough that changes or worsens over time

• Shortness of breath and wheezing

• Bloodstained sputum or phlegm

• Chest pain

• Recurrent chest infections and fever

• Headaches

• Sudden and unexplained weight loss

• Loss of appetite

• General weakness and tiredness

• Bone pain

When to see a doctor

“A persistent cough, wheezing and chest pain can be caused by other conditions as well and may not necessarily indicate lung cancer. It is therefore important to consult your doctor if any of the symptoms of lung cancer persist or are bothering you,” advises Clin Assoc Prof Tan.

Risk factors for lung cancer

A number of different behaviours and environmental exposure are known to increase the risk of developing lung cancer such as: 

• Cigarette, pipe or cigar smoking or vaping: Cigarette smoking is the most common risk factor for lung cancer and is estimated to be responsible for between 80% to 90% of deaths related to lung cancer. The risk of lung cancer developing in a smoker is 15-30 times more than for a non-smoker and increases the longer the duration and/or quantity smoked. 

• Being exposed to industrial hazards: Exposure to certain harmful chemicals and minerals increases the risk of lung cancer (e.g. asbestos, coal gas, chromates, nickel, arsenic, vinyl chloride, mustard gas, radon, by products of uranium, mining processing).

• Passive smoking: This refers to non-smokers who are exposed to second-hand smoke. Being exposed to cigarette smoke increases risk of developing lung cancer by 20-30%.

Why non-smokers can also develop lung cancer

Despite the strong association of smoking with lung cancer, nearly half of the lung cancer cases in Singapore occur in people who have never smoked. 

Given the higher proportion of never-smokers who develop lung cancer in Singapore and Asia, which is a stark contrast to the West, it is likely that additional genetic susceptibilities or environmental and lifestyle risks remain unidentified. 

Family history of lung cancer has also been associated with a higher lung cancer risk. 

Further evidence generated from local population research will enable us to better understand causative links between lung cancer and the East Asian, never-smoker phenotype, as well as to develop lung cancer screening guidelines in Singapore. 

Diagnosing lung cancer

If you have symptoms of lung cancer, your doctor will ask you to undergo the following tests:

• An X-ray and/or CT (Computed Tomography) scan of the lungs

• Sputum exam

• Bronchoscopy – a specialist uses a flexible tubing to examine the airways and possibly do a biopsy (removing small pieces of tissue for examination)

Once lung cancer has been diagnosed, your doctor will determine the stage of the cancer.

• Stage 1 – Cancer is limited to the lung and the tumour is smaller than 5cm in width

• Stage 2 – Cancer may have spread to the chest wall or nearby lymph nodes

• Stage 3 – Tumour may have grown large in size and may have affected other organs or lymph nodes that are further away

• Stage 4 – Cancer may have spread to the other lung or distant areas of the body

Determining the stage of the lung cancer may require further tests such as a bone scan, CT scan, positron emission tomography (PET) scan or an MRI (magnetic resonance imaging).

“Most people diagnosed with lung cancer are over the age of 40. However, the onset of the disease may be years earlier,” says Clin Assoc Prof Tan.

See the previous page to learn what is the main cause of lung cancer in Singapore.

See the next page for the treatment options for lung cancer.

See page 4 to learn how the latest drug therapy can lead to better outcomes. 

Ref: G25 (ed)

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