Ligand‐targeted polymerase chain reaction for the detection of folate receptor‐positive circulating tumour cells as a potential diagnostic biomarker for pancreatic cancer

OBJECTIVES: To detect folate receptor (FR)‐positive circulating tumour cells (FR(+) CTCs) by using ligand‐targeted polymerase chain reaction (LT‐PCR) in periampullary cancer patients and to investigate the diagnostic value of FR(+) CTCs in distinguishing pancreatic cancer (PC) from benign pancreatic disease. MATERIALS AND METHODS: CTCs were enriched from 3 mL of peripheral blood and portal vein blood by immunomagnetic depletion of leucocytes and were then detected by LT‐PCR. The diagnostic performance of FR(+) CTCs in PC was investigated by receiver‐operating characteristic curve analysis. RESULTS: In total, 57 consecutive patients, including 46 patients with PC, five patients with non‐pancreatic periampullary cancer (non‐PC) and six patients with benign pancreatic diseases, were enrolled. FR(+) CTC levels were significantly higher in patients with malignant diseases (PC and non‐PC) than in patients with benign pancreatic diseases (P < .01). There was no notable difference in CTC levels between patients with PC and those with non‐PC (P > .05). The combination of FR(+) CTCs with carbohydrate antigen 19‐9 (CA19‐9) had better diagnostic efficiency than each of these two markers alone, with high sensitivity (97.8%) and specificity (83.3%). CONCLUSIONS: LT‐PCR is feasible and reliable for detecting FR(+) CTCs in patients with periampullary cancer. FR(+) CTCs, especially when used in combination with CA19‐9, have potential as a biomarker for the diagnosis of PC.