Surveillance of patients with intraductal papillary mucinous neoplasm with and without pancreatectomy with special reference to the incidence of concomitant pancreatic ductal adenocarcinoma

Background: The presence of an intraductal papillary mucinous neoplasm is important in the detection of concomitant pancreatic ductal adenocarcinoma. The aim of this study was to elucidate the incidence and timing of development of concomitant pancreatic ductal adenocarcinoma in patients with and without pancreatectomy for intraductal papillary mucinous neoplasm. Methods: We reviewed retrospectively the surveillance data for 22 patients who underwent pancreatectomy for pancreatic ductal adenocarcinoma concomitant with intraductal papillary mucinous neoplasm (pancreatic ductal adenocarcinoma-resection group), 180 who underwent pancreatectomy for intraductal papillary mucinous neoplasm (intraductal papillary mucinous neoplasm-resection group), and 263 whose intraductal papillary mucinous neoplasms were left untreated (nonresection group). The incidence and timing of the development of a concomitant pancreatic ductal adenocarcinoma during the surveillance of patients with and without partial pancreatectomy for intraductal papillary mucinous neoplasm were investigated using the Kaplan-Meier method. Results: During a median surveillance period of 40 months (range 6–262 months), 5 patients in the pancreatic ductal adenocarcinoma-resection group, 6 in the intraductal papillary mucinous neoplasm-resection group, and 8 in the nonresection group developed concomitant pancreatic ductal adenocarcinoma. The estimated 5-year (17%) and 10-year (56%) cumulative incidences of secondary pancreatic ductal adenocarcinoma in the pancreatic ductal adenocarcinoma-resection group were significantly greater than those in the other two groups (P <.01). Conversely, the difference in the estimated cumulative incidence of concomitant pancreatic ductal adenocarcinoma between the intraductal papillary mucinous neoplasm-resection and nonresection groups was not significant (5-year, 5.0% vs 2.2%; 10-year, 5.0% vs 8.7%; P =.87). Conclusion: Long-term (≥5-year) surveillance in patients with intraductal papillary mucinous neoplasm is necessary and important because of the potential for development of concomitant pancreatic ductal adenocarcinoma. Those with a history of resection of concomitant pancreatic ductal adenocarcinoma at the time of the initial operation are at quite high risk for the development of secondary pancreatic ductal adenocarcinoma.