1. Approximately 50% of lung cancer patients in Singapore are never-smokers, with women disproportionately affected.
2. Asian female non-smokers show higher lung cancer rates than Western counterparts despite lower smoking prevalence.
3. Never-smokers often present with advanced-stage lung cancer, partly because early symptoms are subtle.
4. Genetic mutations common in never-smokers make them more responsive to targeted therapy, improving survival.
Lung cancer isn’t just a smoker’s disease
Lung Cancer in Never-Smokers: A Growing Concern
Patients who have never smoked are being diagnosed with lung cancer — and often at late stages.
A study by the National Cancer Centre Singapore (NCCS) found that:
- 5in 10 lung cancer patients are never-smokers,
- More than half are diagnosed at Stage 3 or 4, and
90% of female with lung cancer are never-smokers
“There are few tell-tale signs. It sneaks up on them to deal a heavy blow. Usual symptoms at the time of lung cancer diagnosis are cough, blood in the phlegm, chest pain, breathlessness and weight loss,” says Clinical Associate Professor Ang Mei-Kim, Senior Consultant from the Division of Medical Oncology at NCCS, a member of the SingHealth group.
Why Asian Women Are More at Risk
Globally, Asian female non-smokers appear more vulnerable.
“Less than 4 per cent of Chinese women in Singapore smoke, yet Singapore has a higher lung cancer rate among women (15.9 cases per 100,000 females) compared to countries like Germany and Italy, where one in five women smoke,” notes Dr Ang.
While the exact cause of lung cancer in never-smokers is not known, the growth of these tumours is often driven by specific changes in a single oncogene.
Risk Factors for Non-Smokers
1. Second-hand Smoke
Exposure at home or work increases lung cancer risk by 25%.
2. Environmental Pollutants
- Radon exposure
- Burning biomass or coal in poorly ventilated spaces
3. Genetic Susceptibility
“A large proportion of lung cancers in never-smokers cannot definitely be associated with any established environmental risk factor… certain genes or changes that occur in the genes may affect a person’s susceptibility to these carcinogens. This is an area of current intense research,” says Dr Ang.
Never-Smokers vs Smokers: Not the Same Lung Cancer
Studies in Singapore and globally show that never-smokers tend to develop different types of lung cancer than smokers — and have higher survival rates.
The Two Main Types of Lung Cancer
1. Small Cell Lung Cancer (SCLC)
- About 15% of all lung cancer cases.
- Found almost exclusively in smokers.
- Grows rapidly, spreads early.
- Generally poorer survival
2. Non-Small Cell Lung Cancer (NSCLC)
- More common type, about 85% of all lung cancer cases.
- Grows more slowly.
- Often stays within the lung longer.
- Better survival outcomes
Why Never-Smokers Respond Better to Treatment
Cancers contain multiple genetic mutations. Certain mutations can be targeted using specialised drugs.
“Studies show that never-smokers have different genetic changes in their lung cancer cells compared to smokers, which may make their lung cancers more responsive to these targeted treatments… leading to better survival outcomes,” explains Dr Ang.
Treatment Options for Lung Cancer
Treatment depends on type and stage — and is similar for smokers and never-smokers.
Stage 1 & 2 NSCLC
- Surgery to remove part or all of the affected lung is the mainstay of treatment for early-stage lung cancer.
- In certain circumstances, patients may be given systemic treatment (i.e. medication) before or after surgery to reduce the risk of cancer recurrence. Radiotherapy may be an option for patients who are not suitable.
Stage 3 NSCLC
- Combined chemotherapy + radiotherapy followed by immunotherapy
- In some cases where the lung tumour is operable, chemotherapy and immunotherapy may be used prior to surgery, and continued thereafter.
Stage 4 NSCLC
- Chemotherapy
- Targeted therapy (if gene mutations are present)
- Immunotherapy
Prevention: What Never-Smokers Can Do
“While lung cancer can strike anyone, there are things that never-smokers can do to better protect themselves,” says Dr Ang.
She recommends:
- Don’t start smoking
- Avoid long-term second-hand smoke
- Maintain a healthy diet, active lifestyle, and regular exercise
Although lifestyle changes cannot directly prevent lung cancer, many studies show associations with lower cancer rates overall.
Ref: F26
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