Pathological Complete Remission of Liver Metastases Correlates With Elimination of Tumor-infiltrating Tregs in Gastric Cancer

BACKGROUND/AIM Tumor-infiltrating Foxp3+ regulatory T-cells (Ti-Tregs) promote tumor progression and contribute to poor prognosis in gastric cancer, but the relationship between Ti-Tregs and response to chemotherapy for liver metastases from gastric cancer (LMGC) is unclear. We estimated the correlation between pathological response to chemotherapy and Ti-Tregs in LMGC. PATIENTS AND METHODS Ti-Tregs were analyzed with immunohistochemistry as CD3+ Foxp3+ cells in patients with synchronous LMGC. RESULTS Of 53 patients with LMGC, 49 received chemotherapy as initial treatment and 10 underwent R0 resection. LMGC disappeared pathologically in 5 resected cases despite radiologically residual disease. Ti-Tregs were found frequently in residual LMGC and primary lesions but rarely in tumor scar tissue. There was no relationship between frequency of CD8+ cells and pathological response. CONCLUSION Marked reduction in Ti-Tregs correlates with pathological complete remission of LMGC. Ti-Tregs may be a biomarker to predict the effects of chemotherapy when used in combination with radiological findings.