Background: Intraductal papillary mucinous neoplasm (IPMN) of the pancreas is often found with distinct pancreatic ductal adenocarcinoma (PDAC) in the same pancreas. The aim of this study was to clarify whether endoscopic retrograde pancreatography (ERP) would be useful for the early detection of concomitant PDACs in patients with IPMNs. Methods: Medical records of 179 patients who were histologically confirmed to have IPMNs after resection between 1987 and 2011 were reviewed. The patients having concomitant PDACs were selected, and the diagnostic abilities to detect concomitant PDACs of computed tomography (CT), magnetic resonance imaging (MRI), endoscopic ultrasonography (EUS), and ERP were compared between early (stages 0-I according to Japanese General Rules for Pancreatic Cancer) and advanced (stages II-IV) PDACs. Results: A total of 23 PDACs developed synchronously or metachronously in 20 patients, and the prevalence of PDACs concomitant with IPMNs was 11.2 % (20/179). Sensitivities of CT (16 vs. 87 %), MRI (29 vs. 93 %), and EUS (29 vs. 92 %) in the early group were significantly lower than those in the advanced group (p < 0.01). On the other hand, the sensitivity of ERP in the early group was as high as that in the advanced group (86 vs. 82 %, respectively, p > 0.99). Among 7 early PDACs, 3 were diagnosed only by ERP. Conclusions: ERP has an important role in the early diagnosis of distinct PDACs in patients with IPMNs. Further investigation is necessary to clarify the indication and the timing of ERP during management of IPMNs in term of early detection of concomitant PDACs.
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