The relationship between the severity of pulmonary fibrosis and the lung cancer stage

Background: The incidence of idiopathic pulmonary fibrosis (IPF) and mortality related to the disease have steadily increased in recent years. The risk of cancer is approximately eight times higher in IPF patients than in the general population. The purpose of this study is to determine whether the severity of IPF is related to the time interval between IPF diagnosis and lung cancer diagnosis and to the stage of lung cancer at diagnosis. Methods: In this retrospective cohort study, we reviewed the medical records of patients with lung cancer after IPF diagnosis from two tertiary hospitals in South Korea between 2003 and 2018. We identified 61 patients diagnosed with lung cancer at least 3 months after being diagnosed with IPF. Results: The included patients had a mean age of 71.0 years, and all but one were men (98.4%). The interval between IPF diagnosis and lung cancer diagnosis was not related to the gender-age-physiology (GAP) stage (p=0.662). However, in cox proportional hazard models, a higher GAP stage was significantly correlated with an advanced lung cancer stage (odds ratio 11.1, p=0.003). Conclusions: The lung cancer stage at diagnosis was higher in patients with a higher GAP stage than in those with a lower GAP stage. Physicians should consider implementing more frequent surveillance with computed tomography scans for patients with advanced IPF.