Lung cancer is a disease that begins in the lungs. Lungs are part of the respiratory system that works together to help you breathe. The respiratory system’s main function is to move fresh air into your body while removing waste gases. 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, our lymph nodes, bones, liver and more.
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:
*Pack years are calculated by multiplying the number of cigarette packs smoked daily by the number of years smoking.
It is also recommended that you eat a diet rich in fruits and vegetables and to exercise regularly.
A number of different behaviours and environmental exposure are known to increase the risk of developing lung cancer such as:
Research has shown that cigarette smoke is packed with cancer-causing substances, called carcinogens. When cigarette smoke is inhaled, the carcinogens cause damage to the cells that line the lungs. As healthy cells are exposed to the smoke, they get damaged and eventually transform into cancerous cells.
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.
Lung cancer can lead to complications such as:
Patients may feel breathless if the lung cancer grows and blocks major airways. Lung cancer can also lead to fluid accumulation around the lungs and heart, making it more difficult for the lungs to expand during inhalation.
Lung cancer can result in bleeding in the airways, which may cause patients to cough up blood and, in some cases, can be severe. However, treatments are available to manage bleeding.
Late-stage lung cancer that has spread, such as to the lining of the lung or to other areas, can lead to pain. Inform your doctor if you experience any pain who can recommend treatments to help manage it.
Lung cancer can lead to fluid accumulation in the chest, known as pleural effusion. This fluid gathers in the pleural space, an area surrounding the affected lung within the chest cavity. Pleural effusion can result in breathlessness. However, there are treatments available to drain the fluid and reduce likelihood of it recurring.
Lung cancer often spreads to other parts of the body such as the brain and bones, causing pain, nausea, headaches or other symptoms depending on the affected organ. Once it spreads beyond the lungs, it is typically considered incurable. However, treatments are available to help manage the symptoms and prolong survival.
Tests and procedures used to diagnose lung cancer include a combination of imaging tests and biopsy of an area of abnormal growth detected on a scan, or on clinical examination.
Examples of these tests:
Small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC) are staged differently.
Molecular / Biomarker testing (for NSCLC)
NSCLC may be further divided into different subtypes based on molecular testing of the lung biopsy specimen for certain genes or proteins. These results are used to determine the type of treatment recommendation.
Molecular testing is usually done on biopsy samples. However, in some situations when the biopsy speccimen is not available, the quantity is not enough for further tests, or where the biopsy cannot be performed, a blood test can be done to determine the molecular profile of the cancer. This is referred to as a "liquid biopsy".
Treatment for lung cancer depends on the type of lung cancer, stage of cancer and general health and fitness of the patient. An individual with cancer should be assessed by a specialist to determine which modality of treatment is best suited for them.
Limited stage disease is usually treated with a combination of chemotherapy and radiotherapy to the lungs and mediastinal lymph nodes. After completion of chemoradiation, radiotherapy to the brain may be recommended to reduce the risk of cancer relapse in the brain. Extensive stage disease is usually treated with a combination of chemotherapy and immunotherapy. Some patients may also be treated with radiotherapy depending on their sites of spread and response to treatment.
Early-stage lung cancer may not cause any noticeable symptoms. At a more advanced stage, lung cancer symptoms may include a persistent cough, chest pains, shortness of breath, blood in the sputum, recurrent chest infections and unexplained weight loss.
Lung cancer risk is influenced by a combination of modifiable and non-modifiable factors. Smoking is the most important modifiable risk factor for lung cancer, as smokers are 15 to 30 times more likely to develop lung cancer than non-smokers. The importance of quitting smoking cannot be overemphasised. In non-smokers, second-hand smoke and environmental exposures at work, such as to asbestos and diesel are also associated with an increased risk for lung cancer. In addition, having a first or second degree relative with lung cancer increases the risk of developing lung cancer.
Lung cancer is usually diagnosed through imaging tests such as X-rays or CT scans, followed by a biopsy of an area of abnormal growth that is detected on the scans. The tissue samples extracted during the biopsy are sent to the laboratory to be examined to confirm the diagnosis of lung cancer.
Lung cancer can be cured in the early stages when the cancer is localised and can be completely removed by surgery. Patients may be given additional treatment before or after surgery to reduce the risk of cancer spread, such as chemotherapy, targeted therapy and/or immunotherapy.
As vaping is relatively new, its long-term impact on the risk of developing lung cancer is not yet well-established. Nonetheless, vaping devices release harmful chemicals which may damage lung tissue and lead to the development of lung cancer over time.
Yes, you can. Lung cancer among never smokers is common in Asia. Associated modifiable risk factors include exposure to second-hand smoke, excessive consumption of meat, as well as air pollution – particularly tiny PM 2.5 particles. Family history has also been shown to be associated with the development of lung cancer, especially amongst never smoking women of Chinese ethnicity. The growth of lung cancer in never smokers is commonly driven by a single genetic alteration in majority of these individuals. Ongoing local population research will enable us to better understand the connection between lung cancer and the Asian, never-smoker patient profile.
