Presence of circulating tumor cells is more significant than tumor stage in characterizing cellular local immunity in colorectal cancer.

Abstract

e16073 Background: The purpose of the study was a correlation analysis of parameters of local immunity and markers of the epithelial-mesenchymal transition (EMT) with the number of circulating tumor cells (CTCs) in patients with stage II-IV colorectal cancer (CRC). Methods: The study included 60 patients newly diagnosed with stage II-IV CRC. CTCs were detected with the Cell Search System (Janssen Diagnostics, LLC) prior to surgery. CTC≤3 were considered negative, CTC > 3 – positive. After surgery, IHC analysis of tumor infiltration with immune system cells was performed with monoclonal antibodies for human CD3, CD4, CD8, CD20 and CD56; expression of EMT-associated proteins (E-cadherin, N-cadherin) was measured. All patients were informed of the goal of the study and provided informed consent. Results: CTC-negative patients with later cancer stages showed the loss of connection between the local levels of CD4+ and CD8+, and in stage IV - between CD3+ and CD4+. Starting from stage III, a negative correlation was observed between the expressions of E- and N-cadherin, not associated with the studied indices of local cellular immunity. The presence of CTCs in all 3 investigated stages of CRC, apparently, causes the loss of many connections between the indicators of the 3 units of local cellular immunity. While negative correlations were revealed between T-, B- and NK-cells in CTC-negative status, in CTC+ their number decreased to 1. An important positive correlation was between local levels of CD3+ and CD8+, indicating the predominance of cytotoxic T cells in the tumor and detected at all stages in CTC-negative patients, losing significance in the presence of CTCs regardless of the stage. In stage II, the only correlation (inverse one) was observed between the parameters of local (CD4+) immunity and the expression of cadherins (E-cadherin), which probably reflected the presence of immunosuppressive and growth-stimulating Tregs fraction among these cells. Conclusions: In general, the presence of CTCs was more significant for the number and nature of interconnections of cellular parameters of the local immunity than the tumor stage.