Preoperative carbohydrate antigen 19.9 level predicts lymph node metastasis in resectable adenocarcinoma of the head of the pancreas: a further plea for biological resectability criteria.

Introduction: Lymph-nodal involvement (N+) represents an adverse prognostic factor after pancreatoduodenectomy (PD) for pancreatic adenocarcinoma (PDAC). Preoperative diagnostic and staging modalities lack sensitivity for identifying N+. This study aimed to investigate preoperative carbohydrate antigen 19.9 (CA 19.9) in predicting the N+ stage in resectable-PDAC (R-PDAC).

Methods: Patients included in a multi-institutional retrospective database of PDs performed for R-PDAC from January 2000 to June 2021 were analysed. A preoperative laboratory value of CA 19.9 greater than 37 U/l was used in univariate and multivariate logistic regression analysis to determine a possible association with N+. Additionally, different cut-offs of CA 19.9 related to the preoperative clinical T (cT) stage was assessed to evaluate the risk of N+.

Results: A total of 2034 PDs from thirteen centres were included in the study. CA 19.9 greater than 37 U/l was significantly associated with higher N+ at univariate and multivariate analysis ( P <0.001). CA 19.9 levels greater than 37 U/l were associated with N+ in 75.9%, 81.3%, and 85.7% of patients, respectively, in cT1, cT2, and cT3 tumours and with higher cut-off values for all cT stages.

Conclusion: Lymph-nodal involvement is strongly related to preoperative CA 19.9 levels. Specially in patients staged as cT3 the CA 19.9 could represent a valid and easy tool to suspect nodal involvement. Due to these findings, R-PDAC patients with elevated CA 19.9 values should be considered in a more biologically advanced stage.