Factors Affecting the Learning Curve in the Endoscopic Ultrasound-Guided Sampling of Solid Pancreatic Lesions: A Prospective Study

BACKGROUND/AIMS: Endosonography is associated with a long learning curve. We aimed to assess variables that may influence the diagnostic outcomes in endoscopic ultrasound-guided fine-needle aspiration/biopsy (EUS-FNA/B) of solid pancreatic tumors regarding the level of endoscopists' experience. METHODS: Consecutive patients undergoing EUS-guided puncture of solid pancreatic tumors (eight endosonographers, including six trainees) were prospectively enrolled. An experienced endosonographer was defined as having performed at least 250 EUS examinations, including 75 FNA/Bs. The final diagnosis was determined by cytopathology, histopathology, or clinical follow-up. RESULTS: In total, 283 EUS-FNA/Bs of solid pancreatic tumors (75.6% malignant) in 239 patients (median age 69 years, 57.6% males) were enrolled. Trainees performed 149/283 (52.7%) of the interventions. Accuracy and sensitivity for detecting malignancy were significantly higher in the expert group than in the trainee group (85.8% vs 73.2%, p=0.01 and 82.5% vs 68.4%, p=0.02). Solid lesions evaluated by an expert using FNB needles showed the best odds for a correct diagnosis (odds ratio, 3.07; 95% confidence interval, 1.15 to 8.23; p=0.02). More experienced endoscopists achieved better accuracy in sampling via the transduodenal approach (86.7% vs 68.5%, p<0.001), in the sampling of malignant lesions (82.5 vs 68.4, p=0.02), and in the sampling of lesions located in the pancreatic head (86.1 vs 69.1, p=0.02). In cases involving these factors, we observed a moderate improvement in the diagnostic accuracy after 40 attempts. CONCLUSIONS: Transduodenal approach, pancreatic head lesions, and malignancy were recognized as the most important clinical factors affecting the learning curve in EUS-FNA/B of solid pancreatic lesions.