Prognostic value of circulating tumor cells in patients with pancreatic cancer: a meta-analysis

Increasing scientific evidences suggest that circulating tumor cells (CTC) in peripheral blood may be a powerful predictor of survival in patients with pancreatic cancer. However, many existing studies have yielded inconclusive results. This meta-analysis aims to assess the prognostic value of CTC in patients with pancreatic cancer. An extensive literary search for relevant studies was conducted on PubMed, Embase, Web of Science, Cochrane Library, CISCOM, CINAHL, Google Scholar, CNKI, and CBM databases from their inception through July 1, 2013. The meta-analysis was then performed using the Stata 12.0 software. Crude hazard ratios (HRs) with 95 % confidence intervals (CIs) were calculated under a fixed or random effect model. Nine cohort studies were included in this meta-analysis with a total of 623 pancreatic cancer patients. This number included 268 CTC-positive patients and 355 CTC-negative patients. Our meta-analysis revealed that patients in the CTC-positive group were significantly associated with poor progression-free survival (PFS) (HR = 1.89, 95 % CI = 1.25-4.00, P < 0.001). Furthermore, pancreatic cancer patients in the CTC-positive group also showed worse overall survival (OS) than those in the CTC-negative group (HR = 1.23, 95 % CI = 0.88-2.08, P < 0.001). Subgroup analysis by ethnicity indicated that CTC-positive patients had poor OS among both Asian and Caucasian populations (all P < 0.05). Further subgroup analyses by detection and treatment methods also suggested that CTC-positive patients showed worser OS than CTC-negative patients in the majority of subgroups (all P < 0.05). No publication bias was detected in this meta-analysis. In conclusion, our meta-analysis suggests that CTC-positive pancreatic cancer patients may have worser PFS and OS than CTC-negative patients. Detection of CTC in peripheral blood may be a promising biomarker for the detection and prognosis of pancreatic cancer.