e15508 Background: The most important stages of metastatic cascade are extravasation and invasion of malignant cells and their surviving in blood. The vast majority of circulating tumor cells (CTC) is destroyed by immune cells. The role of immune system which is able to play not only antitumor but also prooncogenic role is manifested both on local and systemic levels. We studied correlations between lymphocyte subsets` content in blood and in tumor of colorectal cancer patients (II, III, IV stages) with and without CTC. Methods: 60 colorectal cancer patients with II (n = 20), III (n = 20) and IV (n = 20) stages underwent surgery without previous chemotherapy. CTC were measured in blood by CellSearchSystem™ (JanssenDiagnostics, LLC), cell-mediated immunity was assessed in blood by flow cytometry (BD Canto II) and in tissue after surgery by immunohistochemistry; some markers of proliferation and epithelial-mesenchimal transition (EMT) in tumor cells (Ki-67, E- and N-cadherins) were also studied. Criteria of CTC-positive and CTC-negative samples were > 3 and ≤3 respectively. Correlative analysis was performed between the data of the patients with and without CTC in each stage, r was counted. Results: In CTC-positive patients with all the stages the number of strong and moderate correlations between system immunologic factors involving CD8+ appeared to be fewer than in CTC-negative ones (7 vs 19). On the contrary, the number of correlations with T regs in CTC-positive was increased: 5 vs 3 in CTC-negative patients. In patients with CTC > 3 fewer correlations were noted between factors of local and systemic immunity than in CTC-negative ones (9 vs 4 in II stage) and total disruption of all the correlations between system immunologic factors and proliferating tumor cells in III and IV stages was established. Some pathologic correlations appeared in CTC-positive patients like moderate direct one between activated T-lymphocytes` amount and Ki-67+ tumor cells. The number of correlations between intratumoral lymphocytes and tumor cells expressing proliferation and EMT markers in CTC-positive patients was decreased in comparison with CTC-negative ones (4 vs 10 in II stage, 1 vs 9 in III, 2 vs 9 in IV stage). Conclusions: The presence of CTC in colorectal cancer patients rather than tumor stage is associated with imbalance of their systemic and local immunologic factors. This provides some evidence that disruption of interactions in the immune system is at least partly due to CTC.
Abstract 3125: Functional validation of respective gene from a nineteen gene-based risk score classifier, TCA19 as a prognostic indicator and response to immune system of colorectal cancer patients
