59 Background: Circulating tumor cells (CTCs) have been shown to be heterogeneous. This study aimed to identify the prognostic significance of CTCs in patients with gastric cancer, focusing on epithelial mesenchymal transition and perioperative kinetics. Methods: Peripheral blood (7.5 ml) was taken from patients (n = 54) before curative resection, and at 7 days, 1 and 6 months postoperatively. CTCs were enriched using density gradient centrifugation and magnetic-activated cell sorting (negative selection). Cell suspensions were characterized by multi-immunofluorescence staining against cytokeratin (CK) and N-cadherin, and by DAPI staining. CTCs were defined as nucleated cells expressing CK or N-cadherin. Threshold analysis identified 1 CTC/7.5 ml as an optimal cut-off value. The median observation period was 735 days. Results: CTCs were detected in seven patients (24%) with early cancer and 14 patients (56%) with advanced cancer (p < 0.05). Cells were identified as either N-cadherin+/CK−/CD45− or N-cadherin+/CK+/CD45−, but no N-cadherin−/CK+/CD45− cells were observed. The median follow-up period was 24.5 months. After 2 years, postoperative recurrence was detected in nine patients, all of whom had advanced gastric cancer and N-cadherin+/CK−/CD45− CTCs preoperatively. In terms of perioperative kinetics (just before, 7 days and 1 month after surgery), we divided patients with advanced cancer into three risk groups: A, preoperative CTCs ≥1 and increased postoperatively; B, preoperative CTCs ≥1 and decreased postoperatively; C; no preoperative CTCs. The recurrence rates in the above groups were 80% (4/5), 44% (4/9), and 0% (0/11), respectively. Conclusions: Numerous CTCs expressed N-cadherin but not CK. Perioperative measurement of CTCs may be a useful surrogate marker for recurrence risk.
A prospective study on the changes and clinical significance of pre-operative and post-operative circulating tumor cells in resectable gastric cancer
