Prognostic significance of the lymphocyte-to-neutrophil ratio in percutaneous fine-needle aspiration biopsy specimens of advanced nonsmall cell lung carcinoma

BACKGROUND. The prognostic significance of tumor-infiltrating lymphocytes (TILs) in surgically resected carcinomas was reported. To apply this to inoperable non-small cell lung carcinomas (NSCLC) of Stage IIIB-IV, the authors estimated the occurrence of TILs using percutaneous fine-needle aspiration biopsy specimens, and tested the validity of this method. METHODS. The authors defined the L-N index as [L-s/(L-s + N-s) - L-B/(L-B + N-B)], in which Ls and Ns denoted lymphocyte and neutrophil counts in the aspiration smear, and L-B, and N-B, denoted lymphocyte and neutrophil counts in the peripheral blood specimen. The cutoff value was set at twice the standard deviation of the L-N index of 41 smears contaminated with abundant blood. Retrospectively, the authors compared the survival rate of the group with a high L-N index (lymphocyte-dominant group) (n = 12) with the survival rate of the group with a low L-N index (lymphocyte- nondominant group) (n = 60). Then, they performed a prospective study and compared the survival rates of these 2 groups (n = 21 and n = 54). The Cox proportional hazards model was used to determine the effect of the L-N index as a continuous variable and other prognostic factors. The correlation (r) between the L-N index-based grouping (L-N grouping) and the histologic grade of TILs was studied among resected lung tumor specimens (n = 164). RESULTS. in the retrospective and prospective studies, the survival rate was significantly higher in the lymphocyte-dominant group than in the lymphocyte-nondominant group (P = 0.0019 and P = 0.0001). Using multivariate analysis, the L-N index was an independent prognostic factor. A significant correlation was noted between L-N grouping and histologic grade of TILs (r = 0.476). CONCLUSIONS. The L-N index of aspiration smears was found to be an independent prognostic factor for patients with advanced-stage NSCLC. L-N grouping was correlated with the histologic assessment of TILs.