The Prognostic Role of Different Blood Cell Count-to-Lymphocyte Ratios in Patients with Lung Cancer at Diagnosis

Background: Lung cancer (LC) is a complex-to-treat disease and remains the leading cause of cancer-related mortality. Methods: Our aim was to investigate the prognostic role of neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), and monocyte to lymphocyte ratio (MLR) in patients with LC. In this retrospective study, examining the period between 1 June 2020 and 31 May 2024, we recorded consecutive patients who presented to the Department of Respiratory Medicine, University Hospital of Patras, Patras, Greece, and received a first diagnosis of LC. The primary outcome was mortality risk analysis based on NLR, PLR, and MLR at diagnosis. Secondary outcomes included associations of tumor, node, metastasis (TNM) staging, and smoking with NLR, PLR, and MLR at diagnosis. Results: We identified 353 patients with a first diagnosis of LC. The mean age ± SD at the time of diagnosis was 68.1 ± 9.1 years. Most patients were male (77.9%, n = 275) and current or ex-smokers (58.1%, n = 205, and 39.1%, n = 138, respectively). Histological diagnosis was non-small-cell lung cancer (NSCLC), small-cell lung cancer (SCLC), and not otherwise specified (NOS) in 67.1% (n = 237), 29.8% (n = 105), and 3.1% (n = 11) of patients, respectively. Adenocarcinoma NSCLC was more common (40.2%, n = 142) compared to squamous NSCLC (25.5%, n = 90). In 12.9% of patients, we identified EGFR, KRAS, ALK, or BRAF molecular driver mutations, while PD-L1 expression was positive in 20.7% of patients. The majority of enrolled patients presented with advanced stage IV LC at diagnosis (63.2%, n = 223). Kaplan-Meier curves showed that patients with higher than the median NLR and PLR at diagnosis were associated with significantly higher mortality risk compared to those with lower than the median [HR: 0.58, (95% CI: 0.42 to 0.81) p = 0.0009 and HR: 0.71, (95% CI: 0.53 to 0.95) p = 0.02, respectively], while no differences in mortality risk were observed between patients with higher versus lower than the median MLR [HR: 0.84, (95% CI: 0.63 to 1.12) p = 0.22]. With regard to secondary outcomes, no associations between higher versus lower than the median NLR, PLR, or MLR values and TNM staging [4.0 (95% CI: 4.0-4.0) vs. 4.0 (95% CI: 4.0-4.0), p = 0.95, 4.0 (95% CI: 4.0-4.0) vs. 4.0 (95% CI: 4.0-4.0), p = 0.09, 4.0 (95% CI: 4.0-4.0) vs. 4.0 (95% CI: 4.0-4.0), p = 0.4, respectively], as well as smoking status [70 (95% CI: 60-80) vs. 80 (95% CI: 60-80), p = 0.10, 70 (95% CI: 60-80) vs. 80 (95% CI: 60-80), p = 0.46, 80 (95% CI: 60-80) vs. 70 (95% CI: 60-80), p = 0.96, respectively] were reported. Conclusions: NLR and PLR could serve as reliable and clinician-friendly prognosticators of clinical outcomes in patients with LC. Further validation cohorts are sorely needed to prove this notion.