Misty role of postoperative adjuvant therapy in resected invasive intraductal papillary mucinous neoplasm of the pancreas: A multicenter external validation

Introduction: Adjuvant therapy is beneficial in prolonging survival in patients with pancreatic ductal adenocarcinoma (PDAC). How-ever, no clear guidelines are available on the oncologic effect of adjuvant therapy in resected invasive intraductal papillary mucinous neoplasms (inv-IPMN). Methods: In total, 551 patients with PDAC and 67 patients with inv-IPMN of the pancreas were reviewed. For external validation, 46 patients with inv-IPMN from six other Korean institutions were enrolled. Stage-matched survival analysis was conducted. Results: Mean follow-up durations in the inv-IPMN and PDAC groups were 54.13 and 30.82 months, respectively. The overall 5-year survival was significantly better in the resected inv-IPMN group than in the PDAC group in the overall stage-matched analysis (p < 0.001). Comparison of disease-free survival by stage showed a significant difference in overall stage between inv-IPMN and PDAC (p < 0.001). Among patients with stage II disease (p = 0.012) and lymph node metastasis (p = 0.004), adjuvant therapy had a negative effect on overall survival (OS) in patients with resected inv-IPMN. Multicenter external validation did not show a better OS in the adjuvant therapy group. On multivariable analysis, only perineural invasion (PNI) was identified as an adverse prognostic factor in resected inv-IPMN (hazard ratio 4.844; 95% confidence interval 1.696 to 13.838, p = 0.003). Conclusions: Inv-IPMN has a more indolent course than PDAC. PNI was the strongest prognostic factor in the resected inv-IPMN group. Current strategy of adjuvant therapy may not improve the OS in patients with resected inv-IPMN. Further investigations on potential role of adjuvant therapy in inv-IPMN is mandatory.