Neutrophil-to-Lymphocyte Ratio and Platelet-to-Lymphocyte Ratio in Blood to Distinguish Lung Cancer Patients from Healthy Subjects

OBJECTIVE: Inflammation-driven markers play a crucial role in tumorigenesis and tumor progression. The neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) in blood are systemic inflammatory response markers. Some reports have showed that NLR and PLR are related to a poor prognosis in patients with lung cancer. However, little studies have reported whether NLR and PLR can be diagnostic markers for lung cancer. The aim of the current study is to investigate the roles of NLR and PLR in diagnosing lung cancer. METHODS: This study analyzed data from lung cancer patients and healthy individuals in Wuxi People's Hospital Affiliated with Nanjing Medical University. The Mann–Whitney U test was performed to compare differences between the lung cancer group and the control group. Based on white blood cell (WBC) counts, both lung cancer patients and healthy individuals were divided into the low-level group, moderate-level group, and high-level group. The Kruskal-Wallis test was applied to compare differences of NLR and PLR among those groups with different WBC counts. Spearman correlation analysis was used to assess correlations. Receiver operating characteristic (ROC) curves were performed to determine diagnostic accuracy. RESULTS: 210 patients diagnosed with lung cancer and 261 healthy subjects were enrolled in this study. Levels of NLR and PLR increased in the lung cancer group compared with the control group (P < 0.001). For the lung cancer group, NLR levels could rise with the increasing of WBC levels (P < 0.001) while PLR levels had no significant variation with the increasing of WBC levels (P = 0.206). For the control group, NLR levels could rise with the increasing of WBC levels (P < 0.001) while PLR levels would decline with the increasing of WBC levels (P < 0.001). In the lung cancer group, both NLR and PLR had no significant correlations with aspartate transaminase, urea, and glucose. The area under the curve (AUC) with 95% confidence interval (95% CI) of NLR and PLR to distinguish lung cancer patients from healthy subjects was, respectively, 0.684 (0.634-0.735) and 0.623 (0.571-0.674). When NLR and PLR were combined, AUC (95% CI) increased to 0.691 (0.642-0.740). CONCLUSIONS: NLR and PLR alone have moderate ability to distinguish lung cancer patients from healthy subjects. Furthermore, combination forms of NLR and PLR can improve diagnostic ability.