Interstitial lung abnormality in stage IV non-small cell lung cancer: A validation study for the association with poor clinical outcome

Purpose: The presence of interstitial lung abnormality (ILA) at diagnosis of stage IV non-small cell lung cancer (NSCLC) patients has previously shown to be associated with shorter overall survival (OS). The present study aimed to validate the association between ILA and shorter OS in a larger cohort of treatment-naive stage IV NSCLC patients. Materials and methods: This study includes 484 patients (205 men and 279 women) with a pathological diagnosis of stage IV NSCLC with pretreatment baseline CT available for review. ILA was visually scored on the baseline chest CT with a 3-point scale (0 = no ILA, 1= indeterminate for ILA, 2 = ILA) as published previously. Clinical characteristics and overall survival (OS) were compared in patients with ILA score 2 vs. those with ILA score 0 or 1. Results: ILA was present (score 2) on baseline CT in 19 of 484 patients (3.9%, 95%CI2.4-6.1%). Patients with ILA were significantly older (p = 0.0008) and more commonly male (p = 0.03) compared to those with ILA score 0 or 1. Patients with ILA score 2 showed significantly shorter OS compared to those with ILA score 0 or 1 (median OS 9.95 months vs. 16.95 months; p = 0.0002). In multivariate analyses, baseline ILA score 2 remained significant as a marker for shorter OS (HR = 2.09, p = 0.004) after adjustments for age (HR = 1.48; p = 0.001), gender (HR = 1.22, p = 0.06), and smoking (HR = 0.79; p = 0.051). Conclusions: ILA on baseline CT at diagnosis of stage IV NSCLC patients was associated with shorter OS (HR = 2.09, p = 0.004), validating ILA as an independent marker for poor clinical outcome.