Tumor-infiltrating gamma delta T cells predict prognosis and adjuvant chemotherapeutic benefit in patients with gastric cancer

Purpose: Tumor-infiltrating gamma delta T cells (gamma delta TILs) have different prognostic value and functions among various cancers. The aim of the present study was to evaluate the effect of gamma delta TILs in gastric cancer. Patients and methods: A discovery set (n = 190) and a validation set (n = 273) were involved in this study. Patients with TNM II and III disease were used to predict response to 5-fluorouracil (5-FU)-based adjuvant chemotherapy (ACT) in both sets. gamma delta TILs were defined as intense (gamma delta T cells >= 5/HPF) versus nonintense (gamma delta T cells < 5/HPF). Kaplan-Meier curve was plotted to analysis survival. Hazard ratio (HR) and 95% CI associated with gamma delta TILs were evaluated by multivariable Cox models. Findings: The prognostic value of gamma delta TILs in the discovery set (HR, 0.193; 95% CI, 0.097-0.383; P<0.001) was confirmed in the validation set (HR, 0.442; 95% CI, 0.251-0.779; P = 0.005) for overall survival (OS). Patients whose tumors with gamma delta T cells >= 5/HPF could benefit from ACT, with a reduced risk of compromised survival compared with those with gamma delta T cells < 5/HPF (HR, 0.086; 95% CI, 0.023-0.327; P < 0.001 in discovery set; and HR, 0.077; 95% CI, 0.023-0.256; P < 0.001 in validation set). Conclusion: The present study shows that intense gamma delta T cells infiltration is an independent prognostic factor in patients with gastric cancer and is predictive of a survival benefit from adjuvant chemotherapy in patients with TNM II and III disease.