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372was performed to evaluate the effect of CTCs posi-tivity and other parameters to OS and DFS. In Cox hazards regression analysis, cTMN stages are divided into the cStageI +II and III+IV groups.The demographics of the patients in the entire cohort are shown in Table 1. Surgical treatments were performed in 29 patients (76.3%), but cohort also included patients undergoing endoscopic treat-ment, chemotherapy and chemoradiotherapy. Eight of 29 patients who underwent esophagectomy received neoadjuvant therapy.Among these 38 patients, CTCs were detected in only 6 (15.7%) patients, the CTC counts were 1/ 7.5ml of blood sample in 4 patients, 2 in one patient, and 190 in one patient. Therefore, we divided the patients into the CTC-positive and CTC-negative groups. (Table 2). CTC-positive group had higher serum SCC level than the CTC-negative group (p= 0.014), and also CTCs-positive group tended to have more advanced cStage than CTCs-nega-tive group (p=0.055). There were no significant differences between these two groups in other clin-icopathological factors.Regarding survivals, the CTCs-negative group showed better survival curves than CTCs positive- Clinicopathological factors SexAgeMain treatmentPrimary tumor locationPredominant Histological typecT classification*cN classification*cStage*CYFRA CA19-9 SCC CEA ESD: Endoscopic submucosal resection, CRT: ChemoradiotherapyCe: Cervical esophagus, Ut: Upper thoracic esophagus, Mt: Middle thoracic esophagus, Lt: Lower thoracic esophagusWell: Well differentiated Squamous cell carcinoma, Mod: Moderately differentiated Squamous cell carcinoma, poor: poorly differentiated Squamous cell carcinomaCYFRA: cytokeratin fragment, CA19-9: carbohydrate antigen 19-9, SCC: squamous cell carcinoma antigen, CEA: and carcinoembryonic antigen* UICC TNM Classification of Malignant Tumors, 7th ed**not measured in some casesTable 2　Comparison of CTC-positive and CTC-negative casesVariablesMale / Female Operation/ ESD/ CRT/ otherCe/ Ut/ Mt/ Lt Well/ Mod/ Poor/ otherT1/ T2/ T3/ T4N0/ N1/ N2/ N3I/ II/ III/ IVhigh/ normal rangehigh/ normal rangehigh/ normal rangehigh/ normal rangegroup in both OS and DFS, however the differences were not statistically significant (Figure 1 and 2). In multivariate analysis, we chosen CTCs status, cStage, serum SCC level and CEA level as indepen-dent variables based on p-value of less than 0.2. Cox hazards regression model showed that CTCs status was likely to be a prognostic factor, but not statistically significant (OS: Hazard Ratio (HR) =0.358, 95% confidence interval (CI) 0.122-1.502, p =0.062, DFS: HR=0.358, 95% (CI) 0.152-2.323, p =0.455), as shown in Table 3A and 3B .In this study, we investigated the relationships between CTCs and survivals. We could show that patients without CTCs had better survival than those of CTCs positive, however the difference was not statistically significant. In multivariate analysis regarding OS and DFS, we were able to demon-strate that CTCs positivity has a possibility to be prognostic marker. We speculated that these discrepancies might be from small sample size and the heterogeneity of patients’ background. Actu-ally, our enrolled patients included those with early disease that can be treated by endoscopy and those with distant metastasis. We assume that the differ-ences in survivals between CTCs positive and CTC-negative28/ 466.026/ 4/ 2/ 03 /6/ 11/ 129/ 18/ 2/ 313/ 4/ 13/ 213/ 7/ 10/ 212/ 4/ 14/ 23/ 28**2/ 303/ 28**10/ 20**CTC-positive5/ 167.02/ 2/ 1/ 11/ 1/ 3/ 11/ 4 /0/ 12/ 0/ 2/ 22/ 0/ 2/ 22/ 0/ 1/ 32/ 41/ 53/ 30/ 6p-Value0.7880.1100.6300.7270.7320.2570.1710.0550.3250.3850.0140.096ResultsDiscussion