As more than half of newly diagnosed lung cancer patients in East Asia, including Korea, are reported to be never-smokers, experts have pointed out that relying solely on smoking history has limitations in predicting and preventing lung cancer risk in this population.

A collaborative research team led by Professors Hong Kwan Kim and Jung Hee Lee from the Division of Thoracic Surgery at Samsung Medical Center, along with Professor Won Jun Ji and resident Hyun Seok Kwak from the Division of Pulmonology at Asan Medical Center, identified major risk factors contributing to lung cancer development among Korean never-smokers. The findings were recently published in CHEST (Impact Factor 9.2), a leading international journal in respiratory medicine.

The research team conducted a matched case-control study involving 3,000 never-smokers diagnosed with non-small cell lung cancer between 2016 and 2020 at Samsung Medical Center and Asan Medical Center, alongside 3,000 control participants without lung abnormalities. Through detailed analysis, they identified key risk factors associated with lung cancer development in never-smokers.

The study revealed that the presence of chronic lung disease was the most significant risk factor for lung cancer among never-smokers. Even without a history of smoking, individuals with conditions such as chronic obstructive pulmonary disease (COPD) or pulmonary tuberculosis had a 2.91-fold higher risk of developing lung cancer compared with the control group.

In particular, patients with COPD showed a markedly elevated risk — up to 7.26 times higher — suggesting that persistent chronic inflammation in the lungs may play a key role in cancer development among never-smokers.

The study also highlighted the importance of family history and socioeconomic factors. 

Participants with a first-degree relative diagnosed with lung cancer had a 1.23-fold increased risk, which rose to 1.54-fold when a sibling had a history of lung cancer.

In addition, individuals living outside the metropolitan area showed a 2.81-fold higher risk compared with those residing in metropolitan regions, suggesting possible influences from environmental exposure, industrial factors, or disparities in healthcare accessibility.

Unemployment status was associated with a 1.32-fold increased risk, indicating that economic factors may affect health management and access to medical care.

Professor Won Jun Ji of Asan Medical Center emphasized, “This study suggests that lung cancer in never-smokers arises from multiple factors, including underlying diseases, family history, and social and environmental influences, rather than a single cause. Beyond smoking-centered screening systems, new prevention and treatment strategies are needed to identify high-risk individuals even among never-smokers.”

Professor Hong Kwan Kim of Samsung Medical Center added, “Because lung cancer is often perceived as a disease caused solely by smoking, never-smokers may pay less attention to lung health. Even without smoking history, individuals with chronic lung disease or a family history of lung cancer should consider regular check-ups and careful monitoring to enable early detection.”