O77: Invasive intraductal oncocytic papillary neoplasms (IOPN) and adenocarcinomas arising from Intraductal papillary mucinous neoplasms (IPMN): adjuvant chemotherapy, patterns of recurrence and survival

Abstract

Abstract Introduction Invasive intraductal oncocytic papillary neoplasms (IOPNs) are extremely rare and are increasingly being recognised as their own entity, distinct from intraductal papilliary mucinous neoplasism subtypes (IPMN). Their clinicopathologic behaviour, recurrence patterns, response to adjuvant chemotherapy and long-term survival outcomes are unknown compared to adenocarcinomas arising from IPMN but were investigated in the present study. Methods Patients undergoing pancreatic resection between 2010-2020 for invasive IOPNs and adenocarcinoma arising from IPMNs were identified retrospectively from 18 academic pancreatic centers worldwide. Survival analyses were conducted to compare outcome measures between IOPNs and IPMN precursor epithelial subtypes and invasive components. Results Of the 459 patients with invasive IOPN/IPMNs, 20 patients had an invasive IOPN (median age,69; male,n=11), the majority of which were in the pancreatic head (75%) and underwent either a Whipples procedure (40%) or PPPD (35%). After a median follow-up of 6 years, 45% of invasive IOPNs developed recurrence (1-year,30.0%; 5-year,69.2%) and 40% survived follow-up (2-year survival 55.0%, 5-year survival, 30.8%). Recurrence rates and survival of invasive IOPNs were higher than colloid IPMNs (n=64) (p=0.031 and p=0.007) and comparable with ductal IPMNs (n=331) as well as gastric (n=54) and pancreatobiliary (n=111) IPMN subtypes. Invasive IOPN had significantly lower cancer-specific survival compared to colloid carcinomas (p<0.001). Adjuvant chemotherapy did not improve rates of recurrence in invasive IOPN and IPMN subtypes (p>0.05). Conclusions Invasive IOPNs are more aggressive than previously suspected and should be regarded as their own entity. Adjuvant chemotherapy does not reduce rates of recurrence regardless of neoplasm type.