Measurement of Portal Vein Blood Circulating Tumor Cells is Safe and May Correlate With Outcomes in Resected Pancreatic Ductal Adenocarcinoma

Background: This study investigated the safety and feasibility of intraoperative portal vein blood (PVB) collection at the time of pancreatic ductal adenocarcinoma (PDAC) resection. Relationships of circulating tumor cells (CTCs) in PVB and peripheral blood (PB) with overall survival (OS) and recurrence-free survival were studied. Methods: Patients undergoing PDAC resection were offered enrollment in a prospective liquid biopsy protocol. The patients had PB drawn before incision and PVB drawn before tumor mobilization, then again immediately after resection. Using standard CellSearch protocols, CTCs were identified and compared with OS. Results: Of the 34 patients enrolled in this study, 23 (68%) underwent pancreaticoduodenectomy, 8 (23%) underwent distal pancreatectomy, and 3 (9%) underwent total pancreatectomy. Peripheral blood was available for 22 (65%) and PVB for 31 (91%) of the patients. No bleeding or thrombotic complications occurred with the PVB draws. The CTC counts per 7.5 mL of PVB collected before and after resection were highly correlated (R² = 0.89). The study found CTCs in 11 (50%) of 22 PB samples and 22 (71%) of 31 PVB samples. The OS rate at 18 months was 92% for the patients with < 3 CTCs, 71% for the patients with ≥ 3 CTCs per 7.5 mL of PB (p = 0.30), 100% for the patients without PVB CTCs, and 70% for the patients with PVB CTCs (p < 0.01). Conclusions: Collection of PVB during PDAC resection is safe. In this pilot study, PVB CTC counts but not PB CTC counts were significantly correlated with OS. This opens the door for future studies on selective omission of adjuvant chemotherapy for patients treated preoperatively and tailored surveillance intensity for patients without PVB CTCs at PDAC resection.