In Asia, it is common for lung cancer to occur in people who have never smoked. The reasons are currently a subject of intense research and investigation. Dr Darren Lim, a senior consultant in the Division of Medical Oncology at the National Cancer Centre Singapore, highlights other risk factors and what can be done to increase the chances of survival and cure for lung cancer patients. 

Q: Besides smoking, what are the factors that can lead to lung cancer and what can be done? 

Associated modifiable risk factors include exposure to second-hand cigarette smoke and diet, for example increased risk is associated with excessive processed or red meat consumption . The reasons for the observed association with red meat consumption remains unclear and are being studied. 

Family history has also been shown to be associated with the development of lung cancer, particularly among people who have never smoked. With the recent discovery that air pollution (especially tiny PM 2.5 particles) promotes the development of cancer, improving environmental air quality should be a major goal. Continued efforts to reduce smoking among our young, and to adopt a healthy diet and lifestyle are crucial, too. 

Q: What happens when lung cancer develops in people who have never smoked and how are treatments recommended? 

In this case, the growth of the disease is commonly driven by specific changes in a single oncogene (a mutated gene that has the potential to cause cancer). Some of these cancers can be effectively controlled with oral targeted drugs if the change or mutation is known. Hence, it is important to have broad molecular testing done on the tumour so doctors can recommend a suitable drug for treatment. 

Q: What are the chances of survival or cure of lung cancer? 

If lung cancer is detected in its early stages, it is more likely to be cured with the use of surgery in combination with other modalities like chemotherapy and radiation therapy. The addition of other treatments such as oral targeted drugs or immunotherapy may be required to further improve the chance of cure. 

Even if the cancer is diagnosed at a late stage where it has spread to other parts of the body, effective treatment is still available. The aims of treatment would be to control the cancer’s growth rate, reduce symptoms as well as to prolong and improve quality of life, even if a cure is not possible. 

Q: Who should consider low-dose computed tomography (LDCT) for early detection?

Currently, screening is recommended for male heavy smokers aged between 55 and 74 years, who are at the highest risk of developing cancer. There is no screening recommendation for “never-smokers”. 

The National Cancer Centre Singapore will run a large clinical study called SingapOre Lung cancer Screening Through Integrating CT with other biomarkErs (SOLSTICE) to assess the impact of screening with LDCT in both smokers and “never-smokers” with relevant risk factors. Supported by the National Medical Research Council and in partnership with the Singapore Cancer Society, it will begin enrolment in 2023. 

Visit to join a free lung cancer webinar on Nov 19, 2022

Dr Darren Lim
Member of Singapore Cancer Society Lung Cancer Committee
Senior Consultant,
Division of Medical Oncology
National Cancer Centre Singapore