Inhaled corticosteroids in COPD and the risk of lung cancer

Inhaled corticosteroids (ICS) might reduce the risk of lung cancer by controlling airway inflammation in patients with chronic obstructive pulmonary disease (COPD) because both are associated with chronic inflammation. The objective was to assess the impact of ICS on lung cancer risk reduction in COPD patients. We performed a nested case–control study based on the database of the National Health Insurance Service–National Sample Cohort, a nationally representative cohort of 1,125,691 participants in Korea followed over 11 years. The eligible population was patients aged 30–89 years who were newly diagnosed with COPD and initiated inhaled medications after diagnosis. Cases were defined as individuals diagnosed with lung cancer after the initiation of inhaled medications and were matched with controls by propensity score at a 1:4 ratio. We identified 265 individuals with lung cancer, matched with 1,060 controls. Use of ICS was associated with reduced risk of lung cancer (adjusted hazard ratio [aHR] 0.74, 95% CI 0.57–0.96). The high cumulative ICS dose group, defined as those above the third quartile of ICS dose distribution, had a lower risk of lung cancer than the low cumulative dose group (aHR 0.51, 95% CI 0.34–0.75). The effect of ICS on lung cancer risk reduction was more remarkable in former smokers than current smokers. Additionally, the result was consistent in men regardless of the classification according to ICS use, while it was not significant in women. ICS, particularly at high cumulative dose, might be associated with decreased risk of lung cancer in patients with COPD. Severe COPD frequently warrants treatment with inhaled corticosteroids, which exert immunomodulatory and antiproliferative effects. Despite an association between COPD and increased lung cancer risk, patients on ICS appear to have a reduced likelihood of developing lung cancer. Here, analyzing data from the National Health Insurance Service–National Sample Cohort in Korea, the authors show that ICS use is associated with decreased lung cancer risk in COPD patients. An inverse dose–response relationship was detected, whereby increasing cumulative ICS dose was associated with decreasing lung cancer risk. The effect was most pronounced in men and former smokers.