Prognostic value of circulating tumor cells in the peripheral blood of patients with esophageal squamous cell carcinoma

OBJECTIVE: Circulating tumor cells (CTCs) of patients with malignant tumors can be used as a prognostic marker. However, there are few relevant reports to date on esophageal squamous cell carcinoma (ESCC). Our study assesses the clinical significance of CTCs in ESCC patients. PATIENTS AND METHODS: CTCs were detected in 103 peripheral blood (PB) samples from 59 ESCC patients. Correlation between CTCs and clinical parameters was analyzed using the χ(2) test or Fisher’s exact test. Overall survival (OS) and progression-free survival (PFS) were analyzed using Kaplan–Meier analysis and univariate and multivariate methods. RESULTS: The CTC detection rate was 79.7% (47/59) at baseline. The frequency of CTC-positive patients increased as the disease stage advanced (88.0% in stages III–IV, 58.9% in stages I–II). CTC counts ≥0/7.5 mL of PB were correlated with the degree of tumor differentiation, tumor infiltration, and lymph node and distant metastases. Overall, the OS and PFS of patients with CTC counts ≥3 or ≥5/7.5 mL of PB before surgery were significantly shorter than those of patients with CTC counts <3 or <5/7.5 mL. Multivariate analysis showed CTC counts ≥5/7.5 mL of PB to be a strong prognostic indicator of OS (hazard ratio [HR] 12.478; 95% confidence interval [CI], 8.2–34.3; P<0.05) and PFS (HR 6.524; 95% CI, 1.2–34.3; P<0.05) in ESCC patients. Patients in whom CTCs changed from positive at baseline to a negative value after surgery had an excellent prognosis. CONCLUSION: CTCs might serve as a reference indicator for the prognosis and monitoring of disease progression and treatment effects in ESCC.