From the Guidelines
Approximately 25% of lung cancer patients are non-smokers, with 15% of lung cancers in men and 53% in women not attributable to smoking. This significant minority of cases occurs in people who have never smoked or smoked fewer than 100 cigarettes in their lifetime. Non-smoking lung cancer patients often develop adenocarcinoma, a specific type of non-small cell lung cancer. Several factors contribute to lung cancer in non-smokers, including secondhand smoke exposure, radon gas, occupational carcinogens (like asbestos, arsenic, and diesel exhaust), air pollution, and genetic factors. Some non-smokers have genetic mutations, particularly in the EGFR gene, that predispose them to lung cancer 1. Family history can also play a role, as can prior lung diseases that cause scarring. The risk increases with age, and women non-smokers appear to develop lung cancer at higher rates than men non-smokers.
Key Factors Contributing to Lung Cancer in Non-Smokers
- Secondhand smoke exposure
- Radon gas
- Occupational carcinogens (like asbestos, arsenic, and diesel exhaust)
- Air pollution
- Genetic factors, including mutations in the EGFR gene 1
- Family history
- Prior lung diseases that cause scarring
Importance of Understanding Non-Smoking Related Lung Cancer
This understanding is important because it highlights that while smoking remains the primary risk factor for lung cancer, anyone with lungs can develop the disease. The prevalence of lung cancer in non-smokers varies by gender, with women being more likely to develop lung cancer than men 1.
Recent Studies and Guidelines
Recent studies have shown that the proportion of non-small cell lung cancer (NSCLC) patients who are never smokers has been increasing, especially in Asian countries 1. The World Health Organization (WHO) estimates that lung cancer is the cause of 1.59 million deaths globally per year, with 71% of them caused by smoking 1. Guidelines for the diagnosis, treatment, and follow-up of lung cancer have been established by organizations such as the European Society for Medical Oncology (ESMO) 1.
From the Research
Lung Cancer in Non-Smokers
- The percentage of lung cancer patients who are non-smokers is estimated to be around 10-15% 2, 3, 4.
- However, one study suggests that this percentage could be as high as 25% 5, 4.
- Non-smokers with lung cancer are more likely to be female and have adenocarcinoma histology 2, 3, 6.
- They also tend to have fewer comorbidities and better overall survival rates compared to smokers with lung cancer 2, 6.
Risk Factors for Lung Cancer in Non-Smokers
- Exposure to radon, asbestos, and arsenic are emerging players in lung tumorigenesis 4.
- Other risk factors include second-hand smoking, occupational exposure to carcinogens, and indoor coal burning 3, 5.
- Infections such as HPV and Mycobacterium tuberculosis, as well as hormonal and dietary factors, have also been reported as potential risk factors 5.
- Having an affected relative and certain single nucleotide polymorphisms can also increase the risk of lung cancer in non-smokers 5.
Survival Outcomes for Non-Smokers with Lung Cancer
- Never smokers with lung cancer tend to have better short- and long-term survival outcomes compared to smokers 6.
- Age, stage at diagnosis, and history of diabetes are significant prognostic factors for survival among non-smokers 6.
- Further studies are needed to validate these findings and explain the mechanistic drivers for improved outcomes among non-smokers 6.