Risk factors for acute exacerbation in lung cancer complicated by interstitial lung disease with slight reticular shadows

BACKGROUND: The risk of cancer treatment‐related acute exacerbation (AE) in patients with lung cancer and mild interstitial lung disease (ILD) on imaging, classified as indeterminate for usual interstitial pneumonia (UIP), has not previously been clarified. METHODS: We retrospectively reviewed the clinical records of 27 patients with lung cancer and ILD who were diagnosed and treated from April 2016 to March 2021. RESULTS: Among the 27 patients, 21 were classified as indeterminate for UIP and six as UIP/probable UIP; furthermore, 10 (46.6%) and three (50%) patients from each group, respectively, developed treatment‐related AEs. No significant difference was observed regarding the incidence of AEs between the two groups. However, significantly more patients in the AE group received immune checkpoint inhibitors (ICIs) compared to the non‐AE group (p = 0.021). Multivariate analysis revealed that the use of ICIs was a significant independent risk factor for treatment‐related AEs. CONCLUSIONS: Lung cancer patients with mild ILD suggestive of indeterminate for UIP and UIP patterns are at an increased risk for treatment‐related AEs. Furthermore, ICI use is an independent risk factor for AEs in patients with lung cancer complicated by ILD, and ICIs should be used with great caution.