Pretest prediction and diagnosis of metastatic lesions to the pancreas by endoscopic ultrasound-guided fine needle aspiration

Background and Aim: Early diagnosis of solid pancreatic lesions (SPLs) enables prompt treatment. The study aims to identify factors differentiating metastatic lesion to the pancreas (PMET) from pancreatic ductal adenocarcinoma (PDAC) and pancreatic neuroendocrine tumors (PNETs). Methods: This is a retrospective study at a tertiary cancer center. Consecutive patients referred for endoscopic ultrasound (EUS) of SPLs from 2004 to 2011 were reviewed. The main outcomes were pre-EUS-FNA (endoscopic ultrasound-guided fine needle aspiration) predictors and diagnostic accuracy of EUS-FNA for PMETs. Results: Among a total of 1108 EUS-FNAs for pancreatic lesions, 672 patients had neoplastic SPLs (PMETs = 53; PDACs = 528, PNETs = 91). The sensitivity, specificity, positive predictive value, and accuracy of EUS-FNA for diagnosis of PMETs were 84.9%, 100%, 100%, and 98.8%, respectively. The mean number of EUS-FNA passes for diagnosis of PMET was 3.1 per patient. For each endosonographer, preceding 3-year EUS volume (mean/year) significantly correlated with fewer needle passes (r_s[-0.30], P = 0.03). The most common PMET was renal cell carcinoma. Stratified multivariate analyses were performed. Compared with patients with PDACs, PMETs were more common in men (odds ratio [OR] = 2.0; 95% confidence interval [CI] = 1.0-4.0); located in the pancreatic tail (OR = 2.4; 95%CI = 1.1-5.2); and were less likely with increasing age (OR = 0.95; 95%CI = 0.92-0.99), presence of major symptoms (abdomen pain/diarrhea/weight loss; OR = 0.2; 95%CI = 0.1-0.4), elevated bilirubin (OR = 0.3; 95%CI = 0.13-0.69), and imaging evidence of arterial invasion (OR = 0.15; 95%CI = 0.03-0.67). Compared with PNETs, PMETs were more common with increase age (OR=1.05; 95%CI = 1.02-1.08) and increasing lesion size (OR = 1.03; 95%CI = 1.0-1.1), and were less likely in patients with diabetes (OR = 0.34; 95%CI = 0.11-0.99). Conclusion: Among the largest numbers of neoplastic SPLs evaluated at a single center, pre-test features reliably characterize, and EUS-FNA provides a highly specific diagnosis of PMETs.