Chronic Lung Disease Raises Cancer Risk Sevenfold in Non-Smokers

South Korean researchers have identified key risk factors that can significantly increase lung cancer rates even in people who have never smoked.

Samsung Medical Center announced on June 11 that a joint research team led by Professors Kim Hong-kwan and Lee Jung-hee from the hospital's Thoracic and Esophageal Surgery Department, along with Professor Ji Won-jun from Asan Medical Center's Pulmonology Department, conducted a detailed analysis comparing 3,000 non-smokers diagnosed with non-small cell lung cancer at both hospitals between 2016 and 2020 against 3,000 control subjects with no lung abnormalities. The study found that a history of chronic lung disease nearly triples the risk of developing lung cancer.

Smoking is the most well-known risk factor for lung cancer. However, lung cancer rates among non-smokers have risen sharply in recent years. In East Asia, including South Korea, more than half of new lung cancer patients are non-smokers. According to the Korean Association for Lung Cancer, 88% of female lung cancer patients in South Korea are non-smokers. Medical experts have pointed out that relying solely on smoking history has limitations in predicting and preventing lung cancer risk.

All 6,000 participants in the study were non-smokers with no history of tobacco use. The analysis showed that non-smokers with a history of lung diseases such as pulmonary tuberculosis had a 2.91 times higher risk of developing lung cancer compared to the control group. For patients with chronic obstructive pulmonary disease (COPD), the risk of lung cancer soared to 7.26 times higher.

The presence of chronic lung disease was confirmed as the strongest risk factor for lung cancer development in non-smokers. The researchers attributed this elevated risk to persistent chronic inflammatory responses in the lungs.

Family history and socioeconomic factors also contributed to lung cancer development in non-smokers. Having a first-degree relative with lung cancer increased the risk by 1.23 times. When siblings had a history of lung cancer, the risk rose to 1.54 times. Residents outside the Seoul metropolitan area faced a 2.81 times higher lung cancer risk than those living in the capital region. Unemployment was also associated with a 1.32 times increased risk. The researchers suggested that regional differences in industrial environmental exposure and healthcare accessibility likely played combined roles. They interpreted that economic factors affect health management and healthcare utilization.

"We need new prevention and treatment strategies that go beyond the current smoker-focused screening system to identify high-risk groups among non-smokers," Professor Ji Won-jun emphasized.

"Because of the perception that lung cancer is caused by smoking, non-smokers tend to neglect their lung health," Professor Kim Hong-kwan advised. "Even if you don't smoke, if you have chronic lung disease or a family history of lung cancer, you should make efforts to detect lung cancer early through regular check-ups and careful management."

The study was published in a recent issue of CHEST, an international respiratory medicine journal.