Risk factors for postoperative recurrence of intraductal papillary mucinous neoplasms of the pancreas based on a long-term follow-up study: proposals for follow-up strategies

Background The aim of this study was to examine the associations between postoperative clinicopathological features of intraductal papillary mucinous neoplasm (IPMN) and recurrence over a long follow-up period. Methods We retrospectively assessed 153 IPMN patients who underwent resection. Results The resected tumors showed low/intermediate-grade dysplasia (LGD/IGD), high-grade dysplasia (HGD), T1a (stromal invasion <= 5 mm), and invasive intraductal papillary mucinous carcinoma (IPMC), in 54.9%, 22.2%, 4.6%, and 18.3% of patients, respectively. The median follow-up period after surgery was 46.4 (6.0-216.3) months, with an overall recurrence rate of 17.0%; the recurrence rates by histological type were 6.0%, 5.9%, 42.9%, and 57.1% for LGD/IGD, HGD, T1a, and invasive IPMC, respectively. Multivariate analysis revealed that recurrences related with tumor location, mural nodule size, presence of invasive cancer, lymph node metastasis, IPMN in the remnant pancreas, and main pancreatic duct dilatation after surgery. Recurrence occurred within the remnant pancreas in all LGD-T1a patients and as extrapancreatic metastasis in all patients with invasive IPMC. Of the total recurrences, 15.4% occurred over 5 years postoperatively. Conclusions The postoperative follow-up protocol for patients with LGD-T1a should be similar to non-resected IPMN, and that for invasive IPMC should be the same as for pancreatic ductal adenocarcinoma patients.