Clinical significance of circulating tumor cells in blood from patients with gastrointestinal cancers

Background: Circulating tumor cells (CTCs) measured by the CellSearch system in metastatic breast cancer have been reported to correlate with shorter overall survival. The purpose of this study was to clarify the clinicopathologic characteristics of CTCs in gastrointestinal cancers. Methods: Pre- and postoperative CTCs from 130 gastrointestinal cancer patients and 41 healthy volunteers were measured by this system. Correlation between CTC counts and clinicopathologic variables was examined. Results: The number of CTCs in metastatic patients (n = 79) was larger than in nonmetastatic patients (n = 35) and in healthy donors (n = 41) (P < 0.001). CTC counts were larger in metastatic gastric cancer (n = 27) than in nonmetastatic gastric cancer (n = 14) (P = 0.016). Two or more CTCs was significantly correlated with advanced tumor stage in all gastrointestinal cancers (P < 0.001) and in gastric cancer (P = 0.032). Two or more CTCs had significant correlation with peritoneal dissemination of gastric or colorectal cancer (P = 0.007) and pleural dissemination of esophageal cancer (P = 0.033). The survival of patients with ≥2 CTCs was shorter than that of patients with <2 CTCs (P = 0.005). The change in CTCs tended to correlate with disease progression and chemotherapeutic effect. Conclusion: This study suggests that measurement of CTCs in gastrointestinal cancer patients could be useful as a tool for judging tumor stage, predicting the presence of peritoneal or pleural dissemination and patients' survival, and monitoring response to cancer therapy.