Invasive intraductal oncocytic papillary neoplasms (IOPN) and adenocarcimoma arising from intraductal papillary mucinous neoplasms (A-IPMN) of the pancreas: comparative analysis of clinicopathological features, patterns of recurrence and survival: a multicentre study

Background: Intraductal oncocytic papillary neoplasms (IOPNs) of the pancreas are now considered a separate entity to intraductal papillary mucinous neoplasms (IPMN). Invasive IOPNs are extremely rare, and their recurrence patterns, response to adjuvant chemotherapy and long-term survival outcomes are unknown. Methods: Consecutive patients undergoing pancreatic resection (2010–2020) for invasive IOPNs or adenocarcinoma arising from IPMN (A-IPMN) from 18 academic pancreatic centers worldwide were included. Outcomes of invasive IOPNs were compared with A-IPMN invasive subtypes (ductal and colloid A-IPMN). Results: 415 patients were included: 20 invasive IOPN, 331 ductal A-IPMN and 64 colloid A-IPMN. After a median follow-up of 6-years, 45% and 60% of invasive IOPNs had developed recurrence and died, respectively. There was no significant difference in recurrence or overall survival between invasive IOPN and ductal A-IPMN. Overall survival of invasive IOPNs was inferior to colloid A-IPMNs (median time of survival 24.4 months vs. 86.7, months, p = 0.013), but the difference in recurrence only showed borderline significance (median time to recurrence, 22.5 months vs. 78.5 months, p = 0.132). Adjuvant chemotherapy, after accounting for high-risk features, did not reduce rates of recurrence in invasive IOPN (p = 0.443), ductal carcinoma (p = 0.192) or colloid carcinoma (p = 0.574). Conclusions: Invasive IOPNs should be considered an aggressive cancer with a recurrence rate and prognosis consistent with ductal type A-IPMN.