Role of Systemic Inflammatory Markers in the Differential Diagnosis of Organizing Pneumonia and Lung Cancer

To investigate novel inflammatory indexes including neutrophil-to-lymphocyte ratio (NLR), systemic immune inflammation index (SII), systemic immune response index (SIRI), and pan-immune-inflammation value (PIV) in the diagnosis of organizing pneumonia (OP) and distinguishing OP from lung cancer (LC). The study included 125 patients with LC and 21 patients with OP. Retrospectively, we compared the values of SII, SIRI, PIV, NLR, and C-reactive protein (CRP) and evaluated correlations between the patient groups. The CRP levels in patients with OP (median: 45.2 mg/dL) were lower than those in patients with LC (median: 64 mg/dL). However, no differences were observed in systemic inflammatory indexes between the groups. Statistically significant positive correlations were found between neutrophils and NLR (r = 0.63), SIRI (r = 0.52), and SII (r = 0.72). In addition, significant negative correlations were observed between lymphocytes and NLR (r = −0.67), SIRI (r = −0.53), SII (r = −0.27), and PIV (r = −0.37). Increased CRP levels may indicate lung carcinoma risk and CRP measurements may be predictive in distinguishing between OP and LC. Additionally, high neutrophil counts, thrombocyte counts and/or lymphocytopenia might lead to a poor immune response and are linked to higher systemic inflammatory indices.