Pirfenidone and risk of lung cancer development in idiopathic pulmonary fibrosis: a nationwide population-based study

Background Idiopathic pulmonary fibrosis (IPF) carries a high risk of lung cancer, but the effect of pirfenidone on lung cancer development remains uncertain. We investigated the association between pirfenidone use and lung cancer development in patients with IPF. Methods We included 9938 patients with IPF from the Korean national claims database. Propensity score analysis with inverse probability of treatment weighting (IPTW) and landmark analyses were employed to evaluate lung cancer occurrence according to pirfenidone use. The association was evaluated using Cox regression models adjusted for clinical and socioeconomic variables. A single-centre IPF clinical cohort (n=941) was used for validating the findings. Results The mean patient age was 69.4 years, 73.7% were men and 32.1% received pirfenidone. Lung cancer developed in 766 patients with IPF (7.7%; 21.9 cases per 1000 person-years) during a median follow-up of 3.0 years. After IPTW, the pirfenidone group showed lower incidence (10.4 versus 27.9 cases per 1000 person-years) than the no pirfenidone group. Landmark analysis at 6 months after IPF diagnosis also showed lower incidence of lung cancer in the pirfenidone group than in the no pirfenidone group. Pirfenidone use was independently associated with a reduced lung cancer risk (weighted adjusted hazard ratio (HR) 0.347, 95% CI 0.258–0.466). A clinical cohort showed similar association (weighted adjusted HR 0.716, 95% CI 0.517–0.991). The association persisted across subgroups defined by age or sex. Conclusion Pirfenidone use may be associated with a reduced lung cancer risk in patients with IPF.