Relationship Between Circulating Tumor Cells and Peripheral T-Cells in Patients with Primary Breast Cancer

Background: Detection of circulating tumor cells (CTCs) in the peripheral blood of patients with primary breast cancer is associated with poor clinical outcome. Recent studies have found evidence for immunological influence on tumor cell dormancy. We therefore investigated the relationship between peripheral T-cells and CTCs, as immunological factors may contribute to the fate of CTCs. Materials and Methods: The peripheral blood immune status of 116 patients with primary breast cancer was analyzed by flow cytometry. Results were correlated with the presence of CTCs and clinicopathological parameters of these patients. Results: Appearance of CTCs was significantly associated with grade III tumors (p<0.05). Interestingly, CTC-positive patients presented with a significant increase of peripheral CD95(FAS)-positive T-helper cells. As immune response is regulated by CD95(APO-1/FAS)-CD95ligand interaction and tumor cells induce apoptosis via the CD95/CD95L (ligand) pathway, this might lead to tumor cell escape by apoptotic T-helper cells. Conclusion: Absence of T-cell help at the time of priming may result in a loss of long-term antigen-activation of CD8 lymphocytes and could lead to an ineffective anti-tumor cell response. This might contribute to systemic immunosuppression and open the door for tumor cell dormancy.