{By: Dr Sachin Almel}

Lung cancer has long been synonymous with smoking but an increasingly concerning trend has emerged: a significant proportion of lung cancers are occurring in people who have never smoked. Roughly 10–20% of lung-cancer cases fall into this category. Globally, and particularly in parts of Asia, that figure may be even higher.

Why Is This Happening?

A combination of changing risk landscapes and under-recognised exposures is driving this shift.

• Environmental Exposures: Air-pollution, especially fine particulate matter and diesel exhaust, is increasingly implicated in non-smoker lung cancer. For example, one study linked rising rates of lung cancer among never-smokers to air-pollution exposure. Indoor pollutants matter too: radon gas, asbestos, arsenic, and household cooking fumes (especially from biomass or poorly ventilated stoves) are known risk factors.


• Second-Hand Smoke: Even if the individual never smoked, exposure to tobacco smoke from others remains harmful. Some analysis estimate that 15%-35% of lung cancers in never-smokers may be attributable to passive smoking.


• Genetics And Biology: Lung cancers in never-smokers often represent a different “entity” biologically. They are more likely to present as adenocarcinoma subtype and more frequently show driver mutations such as EGFR or ALK rearrangements.


• Demographics Shifting: Women and people of East Asian descent make up a disproportionate share of lung cancer in never-smokers. One large analysis found 15.7% of women with lung cancer had never smoked versus 9.6% of men.

What Are We Missing?

Despite these trends, there are gaps in awareness, screening, diagnosis, and prevention:

• Awareness: Many non-smokers still perceive lung cancer as a smoker’s disease, delaying suspicion and diagnosis when symptoms occur.


• Screening Limitations: Current lung-cancer screening guidelines centre around smoking history; never-smokers often do not qualify, despite growing absolute risk. 


• Under-Measured Exposures: Indoor air quality, radon, cooking smoke, occupational exposures, especially in low/middle-income settings, are poorly quantified and often overlooked in risk-assessment.


• Prevention Foccus: Because smoking is so dominant as a cause, preventive efforts tend to focus there; other exposures receive less attention.

What Should Clinicians And Public Health-Systems Do?

• Maintain Vigilance: For non-smokers presenting with persistent cough, chest discomfort, or unexplained respiratory symptoms, lung cancer must remain on the differential, even in the absence of a smoking history.


• Expand Risk-Assessment: Ask about indoor/outdoor air-pollution exposure, radon in homes, cooking-fuel use, occupational exposures, second-hand smoke, and family history.


• Advocate For Policy And Environment: Improving indoor-air ventilation, reducing biomass-fuel cooking, testing for radon, controlling ambient air pollution, all are critical.


• Encourage Molecular Profiling: Lung cancer in never-smokers is more likely to harbor actionable mutations; early genomic testing is especially important to guide therapy.


• Educate Public And Professionals: Shift the mindset from “only smokers get lung cancer” to a broader risk-recognition that includes non-smokers. 

[Disclaimer: The information provided in the article is shared by experts and is intended for general informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified healthcare provider with any questions you may have regarding a medical condition.]