Abstract
BACKGROUND: When monitoring patients with an intraductal papillary mucinous neoplasm (IPMN), it is important to consider both IPMN-derived carcinoma and concomitant ductal adenocarcinoma (PDAC). The latter is thought to have a poorer prognosis. We retrospectively analyzed the risk factors for concomitant PDAC in IPMN. METHODS: In total, 547 patients with pancreatic cysts, including IPMNs inappropriate for surgery on initial diagnosis, encountered from April 2005 to June 2019, were reviewed. We performed surveillance by imaging examination once or twice a year. RESULTS: Five IPMNs with high-grade dysplasia and one IPMN associated with invasive carcinoma were encountered. In comparison, 14 concomitant PDACs were encountered. The prognosis was very poor for concomitant PDACs. All 14 PDAC patients had IPMNs. In patients with IPMNs, long-standing diabetes mellitus was the only significant risk factor for concomitant PDAC in both univariate and multivariate analyses (P < 0.001 and P < 0.01, respectively). Furthermore, patients with IPMNs and diabetes mellitus had a high frequency of concomitant PDACs (9.5%, 9/95) in a median 48-month surveillance period. CONCLUSIONS: When monitoring IPMNs, the development of not only IPMN-derived carcinomas but also concomitant PDACs should be considered. During this period, it may be prudent to concentrate on patients with other risk factors for PDAC, such as long-standing diabetes mellitus.