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What is Lung Cancer?

Lung cancer is a type of cancer that starts in the lungs. Cancer from the lungs may spread to other areas of the body4. When the cancer spreads beyond the lungs, it is known as advanced lung cancer or metastatic lung cancer.

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Lung cancer stages
Adapted from Saint John's Cancer Institute

If you have received a lung cancer diagnosis, you are not alone – lung cancer is one of the most common types of cancer1.

In Malaysia, lung cancer was the third most common type of cancer between 2012-2016. Up to 90% of lung cancer cases were diagnosed in the late stages (in Stage III or Stage IV)1.

Staging percentage of trachea, bronchus and lung cancer
Source: Malaysia National Cancer Registry Report 2012-2016

Types of Lung Cancer

There are different types of lung cancer, but the two most common types are:

Non-small cell lung cancer (NSCLC):

The most common type of lung cancer. There are three subtypes5:

  • type-lung-1

    1. Adenocarcinoma – develops from a particular type of cell that produces mucus (phlegm) and is often found in the periphery of the lungs.

  • 2. Squamous cell cancer – this type of lung cancer is often found near the central part of the lung along the major airways (left or right bronchus).

  • type-lung-3

    3. Large-cell carcinoma – large cells and polygonal in shape under microscopy that are largely located at the periphery of the lung6. They tend to grow rapidly and spread more aggressively compared to the other lung cancers7.

Small cell lung cancer (SCLC):

SCLC comprises around 15% of lung cancers and is strongly linked with cigarette smoking and it tends to start in the middle of the lungs5.

Examples of Signs and Symptoms5,8


Persistent cough

Shortness of breath

Shortness of breath






Coughing up blood


Chest pain




Weight loss


Recurrent lung infections


Bone pain

Risk Factors and Prevention

Who is most at risk of lung cancer9?


    • About Lung Cance
    • About Lung Cancer

While the main cause for NSCLC, the most common type of lung cancer, is attributable to smoking and exposure to secondhand tobacco smoke, those who have never smoked or been regularly exposed to tobacco smoke are also at risk.

What are the other risk factors9?
  • risk-factor-1 Exposure to cancer-causing chemicals such as asbestos, silica, and diesel exhaust
  • risk-factor-2 Exposure to radon gas
  • risk-factor-3 Family history of lung cancer
  • risk-factor-4 Exposure to air pollution
  • risk-factor-5

    Previous lung disease, including chronic obstructive pulmonary disease (COPD) or lung infection10

How to help reduce the risk of developing lung cancer11?
  • reduce-lung-cancer-1 Quit smoking
  • reduce-lung-cancer-3 Be careful of exposure to harmful cancer-causing agents at the workplace including asbestos, diesel exhaust and silica
  • reduce-lung-cancer-2 Avoid secondhand smoke

Screening and Diagnosis

Who needs to be screened for lung cancer12?
  • lung-screening-1

    If you are at high risk of lung cancer (current or former smoker), speak to your doctor about screening for lung cancer.

  • lung-screening-2

    If lung cancer is found early, when it is small and before it has spread, it is more likely to be successfully treated.

  • lung-screening-3

    Usually, symptoms of lung cancer do not appear until the disease is already at an advanced stage, Even when lung cancer does cause symptoms, many people may mistake them for other problems, such as an infection or long-term effects from smoking. This may delay the diagnosis.

  • lung-screening-4

    In recent years, a test known as a low-dose CT scan (LDCT) has been studied in people at a higher risk of getting lung cancer. LDCT scans can help find abnormal areas in the lungs that may be cancer.

How is lung cancer diagnosed13?
  • lung-diagnose-1

    To establish a diagnosis, your doctor may ask about your medical history and perform a physical examination. Further diagnostic procedures and blood tests, such as a chest x-ray and computed tomography (CT) scan, may be needed to confirm the presence of lung cancer.

  • lung-diagnose-2

    Once lung cancer has been diagnosed and based on the type of lung cancer, your doctor will conduct further tests to find out the stage of cancer, le. whether the cancer is in its early stages or has spread to other parts of the body (advanced). These include physical exams, imaging tests, laboratory tests (such as blood tests), and biopsies (taking a sample of abnormal tissue to test it further).

    The type and stage of lung cancer will inform the treatment plan.