The significant prognostic value of circulating tumor cells in colorectal cancer: A systematic review and meta-analysis

Background: Circulating tumor cell (CTC) is a promising candidate biomarker for detection, monitoring, and survival prediction of colorectal cancer (CRC). However, the prognostic significance of CTCs in CRC is currently under debate. Here, we performed a meta-analysis to assess the prognostic value of CTC for patients diagnosed with CRC. Methods: A comprehensive literature research had been performed in the Pubmed, Embase Databases, Cochrane Library, Elsevier Science Direct, and China National Knowledge Internet for studies reporting prognostic data of CTCs in CRC patients since December 2016. The main outcome measures were overall survival and progression-free survival. The hazard ratio (HR) and 95% CI were considered to be the effect measures. Subgroup and sensitivity analyses were also performed. We pooled in meta-analysis under a fixed effect or random-effect model according to heterogeneity. Results: A total of 15 published studies containing 3129 patients matched the selection criteria were included in this meta analysis. Overall analyses revealed that the presence of CTCs was significantly associated with poor mortality (overall survival: HR = 2.36, 95% CI: 1.87-2.97; P = 0.006) along with aggressive disease progression (progression-free survival: HR = 1.83, 95% CI: 1.42-2.36; P < 0.00001). Further subgroup analyses demonstrated that CTC-positive patients also had poor overall survival and disease progression in different subsets, including differences in time points of blood collection, detection methods, median follow-up month, and cutoff value of CTC. Conclusion: Meta-analysis provides a strong evidence that the presence of CTCs was an independent prognosticator of poor survival outcomes for patients with CRC. (C) 2018 Elsevier Inc. All rights reserved.