EUS and EUS-FNA diagnosis of suspected pancreatic cystic neoplasms: Is the sum of the parts greater than the CEA?

Abstract

Background: Carcinoembryonic antigen (CEA) is suggested as the single most useful EUS/EUS-FNA derived test for the diagnosis of mucinous pancreatic cysts.

Study aims: To investigate the yield and diagnostic performance of EUS/EUS-FNA on an intention to diagnose basis and to determine the utility of the recommended CEA and amylase cut-off values.

Patients and methods: A retrospective study of a prospectively maintained database of 433 procedures performed in a 10 year period. Diagnostic performance of EUS-FNA was determined in 133 procedures with a definite diagnosis.

Results: CEA value was determined in significantly fewer procedures (58.6%) than EUS diagnosis was stated (83.4%; p < 0.0001), cyst fluid appearance recorded (89.4%) or adequate sample for cytology obtained (76.7%; p < 0.005). Median CEA was significantly higher in mucinous cysts than non-mucinous (175 ng/ml vs 3 ng/ml, p < 0.0001) and in malignant cysts compared to benign (8945 ng/ml vs 93 ng/ml, p < 0.001). On an intention-to-diagnose analysis, a CEA cut-off of 110 ng/ml was significantly less accurate (42.8%) than EUS diagnosis (67.7%), cytology (58.6%) or aspirate appearance (66.9%; p < 0.05 for all comparisons). However, the combination of EUS diagnosis, cytology and CEA provided higher sensitivity (91%), specificity (75%) and accuracy (85.7%) than each component test alone (p < 0.05 for all comparisons). Median amylase was significantly higher in benign compared to high-risk mucinous cysts ((11,429IU/L vs. 113IU/L; p < 0.05.

Conclusion: The combination of EUS, cytology and CEA performed well. Malignant cysts had a higher CEA value than benign cysts. On an intention to diagnose basis a CEA cut-off of 110 ng/ml performed poorly.

Keywords: Cytology; Endoscopic ultrasound; Fine needle aspiration; Pancreas cysts; Specificity; Tumour markers.