Value of immune factors for monitoring risk of lung cancer in patients with interstitial lung disease

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