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A) Overall survivalClinicopathological factorsCTCscStage*CEASCCB) Disease-free survivalClinicopathological factorsCTCscStage*CEASCCSCC: squamous cell carcinoma antigen, CEA: carcinoembryonic antigen* UICC TNM Classification of Malignant Tumors, 7th edLog-rank test p= 0.082Figure 1　Overall survival (OS) in the CTC-negative and -positive groupsCTCs negative groups would be clear if patients’ backgrounds were limited to some extent.In addition, we investigated the relationships between the detection of CTCs using the Cell-Search® system and clinicopathological factor for patients with esophageal cancer. Although the Cell-Search® system is approved by the FDA for some adenocarcinomas (breast, colorectal, and prostate cancers)4-9), little has been reported on SqCC. The CTCs detection rate in esophageal squamous cell carcinoma is so low that few studies have been conducted in this area11-13). Actually, the CTCs posi-tivity rate in the present study of esophageal Time（Days）VariablesPositive/ negativeI+II/ III+IV(continuous)(continuous)VariablesPositive/ negativeI+II/ III+IV(continuous)(continuous)Table 3　Long-term outcome and CTCsp-ValueExp(b)0.0620.0060.5190.647Exp(b)p-Value0.4550.0210.3250.802Log-rank test p= 0.240cancer was low, 15.7%. This could be due to the distribution of the patients’ characteristics with relatively early-stage cancers. Among this cohort, 39.5% had a depth of T1, 39.4% had no lymph node metastasis, and 31.5% had cStage I cancer.According to our results, CTCs status was signifi-cantly related to the serum SCC level. SCC is widely found in epithelial cells and known as tumor maker of squamous cell carcinoma, not only esoph-agus but also lung, head and neck and others, known to associated with metastasis and poor prognosis14-16). In addition, in some previous studies, SCC mRNA in lymph nodes or peripheral blood Figure 2　Disease-free survival (DFS) in the CTC-negative and -positive groups95% CI Lower0.1221.2590.9681.2590.3582.2371.0161.00695% CI Lower0.1521.4580.9750.9780.59411.7251.0261.003Time（Days）95% CI Upper1.5023.9731.0673.97395% CI Upper2.32394.2661.0791.029373