Background: Current diagnosis and staging of pancreatic ductal adenocarcinoma (PDAC) has important limitations and better biomarkers are needed to guide initial therapy. We investigated the performance of circulating tumour cells (CTCs) as an adjunctive biomarker at the time of disease presentation.

Background Occult metastatic tumors, below imaging thresholds, are a limitation of staging systems that rely on cross-sectional imaging alone and are a cause of the routine understaging of pancreatic ductal adenocarcinomas (PDACs). We investigated circulating tumor cells (CTCs) as a preoperative predictor of occult metastatic disease and as a prognostic biomarker for PDAC patients. Experimental Design A total of 126 patients (100 with cancer, 26 with benign disease) were enrolled in our study and CTCs were identified and enumerated from 4 mL of venous blood using the microfluidic NanoVelcro assay. CTC enumeration was correlated with clinicopathologic variables and outcomes following both surgical and systemic therapies. Results CTCs were identified in 78% of PDAC patients and CTC counts correlated with increasing stage (ρ = 0.42, ρ < 0.001). Of the 53 patients taken for potentially curative surgery, 13 (24.5%) had occult metastatic disease intraoperatively. Patients with occult disease had significantly more CTCs than patients with local disease only (median 7 vs. 1 CTC, p < 0.0001). At a cutoff of three or more CTCs/4 mL, CTCs correctly identified patients with occult metastatic disease preoperatively (area under the receiver operating characteristic curve 0.82, 95% confidence interval (CI) 0.76–0.98, p < 0.0001). CTCs were a univariate predictor of recurrence-free survival following surgery [hazard ratio (HR) 2.36, 95% CI 1.17–4.78, p = 0.017], as well as an independent predictor of overall survival on multivariate analysis (HR 1.38, 95% CI 1.01–1.88, p = 0.040). Conclusions CTCs show promise as a prognostic biomarker for PDAC patients at all stages of disease being treated both medically and surgically. Furthermore, CTCs demonstrate potential as a preoperative biomarker for identifying patients at high risk of occult metastatic disease.