Prognostic Impact of the Combined Use of CA19-9 and DUPAN-2 in Initially Unresectable Locally Advanced Pancreatic Adenocarcinoma

PURPOSE: Our objective was to investigate the prognostic utility of combined carbohydrate antigen (CA) 19-9 and Duke pancreatic monoclonal antigen type 2 (DUPAN-2) levels in patients undergoing curative-intent surgery for initially unresectable locally advanced (URLA) pancreatic ductal adenocarcinoma (PDAC). METHODS: Data from patients who underwent curative-intent surgery for URLA PDAC from June 2010 to December 2024 were investigated. Eligible patients were grouped into normal/normal (N/N), normal/high (N/H), high/normal (H/N), and high/high (H/H) groups according to CA19-9 and DUPAN-2 levels. Grouping was performed before and after preoperative induction chemotherapy, and survival was compared among the groups. RESULTS: In total, 39 patients were included. Before preoperative chemotherapy, the N/N, N/H, H/N, and H/H groups accounted for 10.3%, 20.5%, 30.8%, and 38.5%, respectively; the H/H group was the largest. After chemotherapy, the four groups accounted for 48.7%, 15.4%, 25.6%, and 10.3%, respectively; the N/N group was the largest. Pre-chemotherapy 5-year overall survival rates were 75.0%, 31.3%, 0%, and 44.9%, respectively (p = 0.427). Among the post-chemotherapy groups, the corresponding rates were 44.3%, 16.7%, 44.4%, and 0%, respectively (p < 0.001); the H/H group had significantly lower survival than the other groups. Multivariate analysis identified the post-chemotherapy H/H group as an independent predictor of poor survival (p = 0.004). CONCLUSIONS: Patient grouping using the two markers after preoperative chemotherapy was associated with overall survival and may be useful for prognostic stratification. In patients being considered for curative-intent surgery, the post-chemotherapy H/H group may warrant careful attention.