Abstract
OBJECTIVE: Patients with interstitial lung disease (ILD) are at increased risk of developing lung cancer. We aimed to investigate the clinical significance of serum immune factors in this progression. METHODS: We retrospectively screened a hospital database from January 2012 to December 2016 for patients with lung cancer and ILD. We measured serum levels of C3, C4, IgA, IgG, IgM, C-reactive protein (CRP), ceruloplasmin (CER), and rheumatoid factor in these patients and in healthy controls. RESULTS: We analyzed data for 262 patients with lung cancer, 220 with ILD, and 57 healthy controls. CER levels were significantly higher in patients with lung cancer (0.35 ± 0.10 g/L) compared with both ILD patients (0.31 ± 0.25 g/L) and healthy individuals (0.25 ± 0.04 g/L). C3 and C4 levels were both significantly higher in healthy individuals compared with patients with lung cancer (C3: 1.70 ± 0.29 vs 1.04 ± 0.26 g/L, C4: 0.27 ± 0.24 vs 0.24 ± 0.09 g/L) and ILD (C3: 1.70 ± 0.29 vs 0.97 ± 0.25 g/L, C4: 0.27 ± 0.24 vs 0.21 ± 0.09 g/L). Optimal scaling analysis demonstrated that lung cancer was closely associated with CRP, CER, C3, and C4. CONCLUSIONS: Increased levels of CRP and CER and decreased levels of C3 and C4 may identify patients with ILD at high risk of developing lung cancer.