Impact of Adjuvant Chemotherapy on Resected Intraductal Papillary Mucinous Neoplasm-Derived Pancreatic Cancer: Results From an International Multicenter Study.

Abstract

The benefit of adjuvant therapy for intraductal papillary mucinous neoplasm (IPMN)-derived pancreatic ductal adenocarcinoma (PDAC) remains unclear because of severely limited evidence. Although biologically distinct entities, adjuvant therapy practices for IPMN-derived PDAC are largely founded on pancreatic intraepithelial neoplasia-derived PDAC. We aimed to evaluate the role of adjuvant chemotherapy in IPMN-derived PDAC. This international multicenter retrospective cohort study (2005-2018) was conceived at the Verona Evidence-Based Medicine meeting. Cox regressions were performed to identify risk-adjusted hazard ratios (HR) associated with overall survival (OS). Kaplan-Meier curves and log-rank tests were employed for survival analysis. Logistic regression was performed to identify factors motivating adjuvant chemotherapy administration. A decision tree was proposed and categorized patients into overtreated, undertreated, and optimally treated cohorts. In 1,031 patients from 16 centers, nodal disease (HR, 2.88, <i>P</i> < .001) and elevated (≥37 to <200 µ/mL, HR, 1.44, <i>P</i> = .006) or markedly elevated (≥200 µ/mL, HR, 2.53, <i>P</i> < .001) carbohydrate antigen 19-9 (CA19-9) were associated with worse OS. Node-positive patients with elevated CA19-9 had an associated 34.4-month improvement in median OS (<i>P</i> = .047) after adjuvant chemotherapy while those with positive nodes and markedly elevated CA19-9 had an associated 12.6-month survival benefit (<i>P</i> < .001). Node-negative patients, regardless of CA19-9, did not have an associated benefit from adjuvant chemotherapy (all <i>P</i> > .05). Based on this model, we observed undertreatment in 18.1% and overtreatment in 61.2% of patients. Factors associated with chemotherapy administration included younger age, R1-margin, poorer differentiation, and nodal disease. Almost half of patients with resected IPMN-derived PDAC may be overtreated or undertreated. In patients with node-negative disease or normal CA19-9, adjuvant chemotherapy is not associated with a survival benefit, whereas those with node-positive disease and elevated CA19-9 have an associated benefit from adjuvant chemotherapy. A decision tree was proposed. Randomized controlled trials are needed for validation.