Tumor Size Reduction and Serum Carbohydrate Antigen 19-9 Kinetics After Neoadjuvant FOLFIRINOX in Patients With Pancreatic Ductal Adenocarcinoma

Abstract

BackgroundChanges in tumor size and serum carbohydrate antigen 19-9 are commonly reported markers used to assess response to neoadjuvant therapy in pancreatic ductal adenocarcinoma. We evaluated the impact of the percentual tumor size reduction and carbohydrate antigen 19-9 kinetics on resectability and response to neoadjuvant FOLFIRINOX. MethodsThis was an institutional analysis of patients with non-metastatic (upfront resectable, borderline resectable, and locally advanced) pancreatic ductal adenocarcinoma who underwent neoadjuvant FOLFIRINOX. Resectability, pathologic response, disease recurrence, and overall survival were evaluated. ResultsAmong 193 patients who completed FOLFIRINOX, 60% underwent resection, and 91% were R0. Pathologically, complete, and near-complete responses were achieved in 4% and 40% of patients, respectively. Tumor size reduction (odds ratio 1.02 per 1%, P = .024) and normalization of carbohydrate antigen 19-9 (odds ratio 2.61, P = .035) were associated with increased odds of resectability. Concerning pathologic response, tumor size reduction (odds ratio 1.03 per 1%, P = .018) was associated with increased odds of a complete and near-complete response. Lastly, in resected patients, a postoperative increase in carbohydrate antigen 19-9 after prior normalization after neoadjuvant therapy were at an increased risk of recurrence (hazard ratio 9.58, P < .001) and worse survival (hazard ratio 10.4, P < .001) compared to patients who maintained normalization. ConclusionIn patients with non-metastatic pancreatic ductal adenocarcinoma who underwent neoadjuvant therapy, tumor size reduction was a significant predictor of resectability and pathologic response, including complete and near complete responses, whereas serum carbohydrate antigen 19-9 normalization predicted resectability, disease recurrence, and survival. Patients with a postoperative carbohydrate antigen 19-9 rise after prior normalization after administration of neoadjuvant therapy were at an increased risk of recurrence and worse overall survival.