Prognostic value of tumor-infiltrating lymphocytes differs depending on histological type and smoking habit in completely resected non-small-cell lung cancer

Background T-cell infiltration in tumors has been used as a prognostic tool in non-small-cell lung cancer (NSCLC). However, the influence of smoking habit and histological type on tumor-infiltrating lymphocytes (TILs) in NSCLC remains unclear. Patients and methods We evaluated the prognostic significance of TILs (CD4+, CD8+, CD20+, and FOXP3+) according to histological type and smoking habit using automatic immunohistochemical staining and cell counting in 218 patients with NSCLC. Results In multivariate survival analyses of clinical, pathological, and immunological factors, a high ratio of FOXP3+ to CD4+ T cells (FOXP3/CD4) [hazard ratio (HR): 4.46, P Conclusions A low number of CD8+ T cells in non-AD, a high FOXP3/CD4 ratio in smokers with AD, and a low number of CD20+ B cells in non-smokers with AD were identified as independent unfavorable prognostic factors in resected NSCLC. Evaluating the influence of histological type and smoking habit on the immunological environment may lead to the establishment of immunological diagnosis and appropriate individualized immunotherapy for NSCLC.