Lung Cancer

What causes 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: 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. 
• 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: Non-smokers who are exposed to second-hand smoke increase their risk of developing lung cancer by 20-30%. 

How smoking causes lung cancer 

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 – Complications 

Lung cancer can lead to complications such as: 

Breathlessness 

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. 

Coughing blood 

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. 

Pain 

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. 

Fluid in the chest 

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. 

Cancer spread 

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.