*University of California, Los Angeles, Los Angeles, California‡Liver and Pancreatobiliary Disease Research Center, Digestive Disease Research Institute, Tehran University of Medical Science, Tehran, Iran§Washington University School of Medicine, St. Louis, Missouri∥University of Colorado Anschutz Medical Campus, Aurora, Colorado¶Kansas City VA Medical Center and University of Kansas, Kansas City, Missouri#Feinberg School of Medicine, Northwestern University, Chicago, Illinois**Arizona Center for Digestive Health, Gilbert, Arizona
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BACKGROUND & AIMSIt is not clear exactly how many passes are required to determine whether pancreatic masses are malignant using endoscopic ultrasound–guided fine-needle aspiration (EUS-FNA). We aimed to define the per-pass diagnostic yield of EUS-FNA for establishing the malignancy of a pancreatic mass, and identify factors associated with detection of malignancies.METHODSIn a prospective study, 239 patients with solid pancreatic masses were randomly assigned to groups that underwent EUS-FNA, with the number of passes determined by an on-site cytopathology evaluation or set at 7 passes, at 3 tertiary referral centers. A final diagnosis of pancreatic malignancy was made based on findings from cytology, surgery, or a follow-up evaluation at least 1 year after EUS-FNA. The cumulative sensitivity of detection of malignancy by EUS-FNA was calculated after each pass; in the primary analysis, lesions categorized as malignant or suspicious were considered as positive findings.RESULTSPancreatic malignancies were found in 202 patients (84.5% of the study population). EUS-FNA detected malignancies with 96% sensitivity (95% confidence interval [CI], 92%–98%); 4 passes of EUS-FNA detected malignancies with 92% sensitivity (95% CI, 87%–95%). Tumor size greater than 2 cm was the only variable associated with positive results from cytology analysis (odds ratio, 7.8; 95% CI, 1.9–31.6). In masses larger than 2 cm, 4 passes of EUS-FNA detected malignancies with 93% sensitivity (95% CI, 89%–96%) and in masses ≤2 cm, 6 passes was associated with 82% sensitivity (95% CI, 61%–93%). Sensitivity of detection did not increase with increasing number of passes.CONCLUSIONSIn a prospective study, we found 4 passes of EUS-FNA to be sufficient to detect malignant pancreatic masses; increasing the number of passes did not increase the sensitivity of detection. Tumor size greater than 2 cm was associated with malignancy, and a greater number of passes may be required to evaluate masses 2 cm or less.ClinicalTrials.govnumber, NCT01386931.