Risk of lung cancer and derived mortality in patients with interstitial lung diseases: A nationwide population-based matched cohort study.

<bold>Introduction:</bold> Interstitial lung disease (ILD) and lung cancer (LC) share risk factors, thus with ILD patients facing an increased risk of LC and derived mortality. However, long-term studies on this field are sparse. This study assesses the risk and prognosis of LC in patients with ILD versus the general Danish population. <bold>Methods:</bold> Utilizing Danish nationwide health registries, we included all patients with ILD (1995-2022), each matched with up to 10 individuals from the general population on birth year and sex. All individuals were followed for up to 10 years from ILD diagnosis to assess LC incidence. LC patients were followed from diagnosis to death. Ten-year LC risks were calculated, and 10-year overall mortality following lung cancer diagnosis was assessed, both using the Aalen-Johansen estimator. <bold>Results:</bold> The study included 34,613 ILD patients (men: 58%, median age: 64 years) and 318,082 matched comparators. LC incidence was 3.0% (95% CI: 2.8, 3.2) in ILD patients and 1.6% (95% CI: 1.6, 1.7) in comparators. After LC diagnosis ILD patients had higher 10-year mortality (80% versus 75%). Older age and male gender were associated with increased LC risk and all-cause mortality. <bold>Conclusion:</bold> Patients with ILD have an increased risk of LC compared to matched comparators and further exhibit a higher mortality risk following LC. Male gender and advanced age further elevate these risks. Due to the high risk, targeted surveillance programs should be considered to facilitate early detection and improve outcomes.