The Role of Circulating Tumor Cell Dynamics in the Prognosis of Colorectal Cancer: A Systematic Review and Meta-Analysis.

OBJECTIVE: The prognostic value of circulating tumor cells (CTCs) in colorectal cancer (CRC) remains debated. This meta-analysis evaluates their role in monitoring treatment response and predicting survival. METHODS: We systematically searched multiple databases up to November 2025. Inclusion criteria comprised cohort studies involving CRC patients that assessed peripheral blood CTCs and reported outcomes such as CTC positivity/levels before and after treatment, progression-free survival (PFS), and overall survival (OS). Two reviewers independently extracted data and assessed the risk of bias using the Newcastle-Ottawa Scale. The meta-analysis was performed using Stata 18.0, with pooled odds ratios (ORs), standardized mean differences (SMDs), and hazard ratios (HRs) calculated using fixed- or random-effects models based on heterogeneity assessed by the I² statistic. This study was registered in PROSPERO. RESULTS: A total of 18 studies involving 2,838 CRC patients were included. The meta-analysis demonstrated a significant decrease in both the CTC-positive rate (OR=0.52, 95% CI 0.31-0.87) and CTC count (SMD=-0.32, 95% CI -0.42 to -0.21) following therapy. Compared to patients without CTC reduction, those with reduced CTCs exhibited significantly better progression-free survival (HR=2.41, 95% CI 1.75-3.31) and overall survival (HR=3.29, 95% CI 1.99-5.45). Furthermore, CTC-positive status, both before and after treatment, was consistently associated with inferior PFS and OS (all p < 0.0001). CONCLUSIONS: CTCs can serve as a biomarker for monitoring CRC therapeutic efficacy, predicting prognosis, and guiding subsequent treatment.