Inhaled corticosteroids and risk of lung cancer among COPD patients who quit smoking

RATIONALE AND OBJECTIVES: COPD is associated with an increased risk of lung cancer. We examined whether inhaled corticosteroids (ICS) used concomitantly with long-acting beta(2)-agonists (LABA) were associated with reduction in lung cancer risk in COPD patients. METHODS: We conducted a retrospective cohort study of patients with a first-time diagnosis of COPD (index date) between 1989 and 2003 who were initially free of lung cancer, had quit smoking, were aged >or=50 years at time of diagnosis, and were regular users of ICS, ICS/LABA concomitantly, or short-acting bronchodilators (SABD). A nested case-control design was applied to overcome the time-varying nature of treatment. RESULTS: We identified 7079 COPD patients who were regular users of the therapies of interest, of whom 127 subsequently had lung cancer and were matched to 1470 controls of same gender and age. Lung cancer was diagnosed in 6.0\% of concomitant ICS/LABA users compared with 7.3\% of ICS and 10.9\% of SABD users. In multivariate analyses, reductions in lung cancer risk were observed, with hazard ratio (HR) 0.50 (95\% confidence interval, 0.27-0.90) in ICS/LABA users and 0.64 (0.42-0.98) in ICS users, compared with SABD users. In assessing 'dose-response' relationships, we found risk reductions: HR of 0.75 (0.33-1.75) and 0.39 (0.19-0.79) in ICS/LABA users with 1-2 and 3+ prescriptions/year, respectively, and 0.88 (0.51-1.52) and 0.51 (0.30-0.84) in ICS users with 1-2 and 3+ prescriptions/year, respectively. CONCLUSIONS: Regular use of ICS, with and without LABA, may reduce the risk of lung cancer among former smokers with diagnosed COPD.