The role of lung cancer in mortality rate in chronic fibrosing idiopathic interstitial pneumonia

The coexistence of chronic fibrosing idiopathic interstitial pneumonia (cf-IIP) and lung cancer (LC) in the same patient raises many doubts regarding patient prognosis and complicates decision-making in multidisciplinary thoracic committees. To provide new insights into the management and prognosis of patients with cf-IIP, we assessed the sociodemographic and clinical differences between patients with and without LC to evaluate their role in their mortality. Other factors were also studied. A longitudinal study was conducted from January 1, 2001, to December 31, 2020, in our hospital. All patients who attended the interstitial lung disease multidisciplinary unit and had a medical diagnosis of cf-IIP were included. The primary outcome was all-cause mortality. The independent variable was the presence of LC. Covariates: sociodemographic, clinical, and therapeutic variables. The mortality rate (MR) was expressed per 1000 patient-years with a 95% confidence interval (CI). Cox multiple regression analysis examined the influence of LC and other covariates on mortality. The results are expressed as hazard ratios (HRs) with CIs. A total of 313 patients with cf-IIP were included, with a follow-up of 1589.6 patient-years. There were 209 (66.8%) deaths. The MR was 131.5 (114.8-150.6), and 50% of patients died at 5.58 years from cf-IIP diagnosis. After adjusting for confounders, LC was associated with a significantly increased risk of mortality (HR 4.11; 2.50-6.77; p = 0.000), whereas antifibrotic treatment was the only factor that decreased the risk of mortality (HR 0.60; 0.43-0.84; p = 0.003). The prevalence of LC was 15.3%. The most common histopathological type was squamous cell carcinoma (39.6%). At diagnosis, 68.7% of LC cases were in stages III-IV. The most widely used treatment was chemotherapy and its combination (43.7%). Patients with cf-IIP who developed LC had a fourfold increased risk of mortality and shorter mean survival (2 years vs. 6 years) compared with those without LC. Therefore, we recommend LC screening in these patients.