Clinical significance of the frequency of regulatory T cells in regional lymph node lymphocytes as a prognostic factor for non-small-cell lung cancer

Abstract

Background: Regulatory T cells (Tregs) are potent immunosuppressive cells that play a crucial role in tumor immune escape. The purpose of the present study was to evaluate the prognostic significance of the frequency of CD4+CD25+Foxp3+ Tregs in the regional lymph node lymphocytes (RLNL) and peripheral blood lymphocytes (PBL) in patients who underwent surgical resection of non-small cell lung cancer (NSCLC).

Methods: The RLNL and PBL in 158 NSCLC patients who underwent complete surgical resection were collected at the time of surgery. The proportions of CD4+CD25+Foxp3+ cells in the RLNL and PBL were determined by flow cytometry.

Results: The average proportions of Tregs in the RLNL and PBL were 1.28% and 0.76%, respectively. The proportion of Tregs in the RLNL was significantly higher than that in the PBL (p < 0.0001). The 5-year overall survival rates of the patients according to the proportion of Tregs in the RLNL were 84.4% and 63.5% in the lower and higher groups, respectively. A significant difference was observed in the survival rate between the higher and lower groups (p = 0.0056). Among the patients with stage I disease, the 5-year survival rate (91.4%) was significantly higher in patients with the lower proportion of Tregs in RLNL that in the higher group (72.1%) (p = 0.0147).

Conclusions: The higher proportion of Tregs in the RLNL was a significant unfavorable prognostic factor, even in patients with node-negative NSCLC. The information about the proportion of Tregs in the RLNL might improve the discriminatory power for assessing the risk of the recurrence of NSCLC.

Keywords: Foxp3; Immune escape mechanism; NSCLC; Regional lymph node lymphocytes; Regulatory T cells; Surgical resection.