S0053 Comparison of EUS-Guided Conventional Smear Cytology and Liquid Based Cytology in Pancreatic Lesions: A Systematic Review and Meta-Analysis

Abstract

INTRODUCTION: EUS guided fine needle aspiration (EUS-FNA) has limitations of inadequate sampling and false-negative results for malignancy. Traditionally it has been performed using conventional smear (CS) cytology with sub-optimal diagnostic accuracy. The addition of rapid on-site evaluation (ROSE) to CS has been shown to improve sensitivity and sample adequacy. However, ROSE is not available in all healthcare centers. An alternative to ROSE is liquid-based cytology (LBC). Commonly used LBC techniques include precipitation-based (SurePath™) and filtration-based (ThinPrep®, CellPrep®). Data regarding the diagnostic efficacy of LBC compared to CS without ROSE is limited. METHODS: Multiple databases were searched through March 2020 to identify studies reporting diagnostic yield of EUS-guided CS and LBC in pancreatic lesions. Pooled diagnostic odds and rates of performance for the cytologic diagnoses of benign, suspicious, and malignant lesions were calculated. Diagnostic efficacy was evaluated by pooled rates of accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV). RESULTS: 9 studies with a total of 1308 patients were included in our final analysis. None of the included studies utilized rapid on-site evaluation (ROSE). CS cytology performed significantly better than filtration-based LBC technique in diagnosing suspicious, and malignant pancreatic lesions [OR = 1.69 (1.02–2.79); P = 0.04, OR = 0.47 (0.27–0.8); P = 0.006]. For benign lesions, outcomes of the two techniques were comparable. Precipitation-based LBC performed significantly better than CS cytology in diagnosing malignant pancreatic lesions [OR = 0.39 (0.19–0.8); P = 0.01], but this effect was not seen with respect to benign lesions. For CS, precipitation-based and filtration-based LBC, pooled diagnostic accuracy was 79.7%, 85.2%, 77.3%, sensitivity was 79.2%, 83.6%, 68.3%, and specificity was 99.4%, 99.5%, 99.5%, respectively. CONCLUSION: Precipitation-based LBC technique (SurePath™) had superior diagnostic odds for malignant pancreatic lesions compared to CS cytology in the absence of ROSE. It showed superior accuracy and sensitivity, but comparable specificity and PPV. Diagnostic odds of CS cytology in the absence of ROSE were superior to filtration-based LBC technique (ThinPrep®, Cellprep®) for diagnosing malignant pancreatic lesions. In the absence of ROSE, precipitation-based LBC should be preferred over conventional smear technique in EUS-guided sampling of pancreatic lesions.Figure 1.: Odds Ratio - Forest Plot.Figure 2.: Pooled Rate - Forest Plot.