Regulatory T-cells and micrometastasis in lymph nodes of stage I NSCLC.

BACKGROUND Regulatory T-cells (Tregs) have a pivotal role not only in abrogating autoimmune disease, but also in tumor immune escape. The purpose of the present study was to evaluate the clinical significance of the relative expression of forkhead/winged helix transcription factor (FOXP3) and micrometastasis in the regional lymph nodes (RLNs) of patients with stage I non-small cell lung cancer (NSCLC). MATERIALS AND METHODS The RLNs in 131 patients who underwent complete surgical resection for stage I NSCLC were collected at the time of surgery. The relative expression levels of FOXP3 and cytokeratin 19 (CK19) in RLNs were determined by quantitative RT-PCR. RESULTS The pathological stage was diagnosed as stage IA in 97 patients (74.0%) and stage IB in 34 patients (26.0%). The relative expression levels of FOXP3 and CK19 in the RLNs were 0.062±0.0083% and 0.025±0.056%, respectively. The relative expression of FOXP3 tended to increase with increasing relative expression of CK19. The five-year overall survival rate of the patients with low expression of FOXP3 was better (90.3%) than that of patients with high expression (79.3%) (p=0.0419). A multivariate analysis using the significant variables (gender, age, histology and FOXP3 expression) showed that the FOXP3 expression in RLNs was a significant independent prognostic factor. CONCLUSION The expression of CK19 tended to be positively correlated with the expression of FOXP3. High expression of FOXP3 in RLNs was a significant unfavorable prognostic factor in patients with stage I NSCLC.