Abstract Introduction Intraductal papillary mucinous neoplasms (IPMNs) are a subset of lesions with elevated malignant potential, warranting their inclusion in screening standards. Despite endoscopic ultrasound (EUS) with fine-needle aspiration biopsy (FNAB) serving as the standard for verification, the occurrence of erroneous conclusions remains significant. Consequently, analysis of pancreatic juice is considered as a potential adjunctive diagnostic method. However, the absence of methods for obtaining pancreatic juice in adequate volume and quality poses a barrier to the widespread adoption of this approach.Materials and MethodsA method of duodenal aspiration biopsy (DAB) was developed involving active aspiration from the lumen of duodenum, yielding large volume of the mix of pancreatic juice and bile uncontaminated by gastric juice. Patients diagnosed with pancreatic neoplasms utilizing EUS with FNAB, were enrolled and ALB was implemented as an adjunctive diagnostic procedure. Cytological analysis of the material obtained was performed along with measuring the level of carcinoembryonic antigen (CEA). The level >192 ng/mL was considered significant, according to the Fukuoka 2017 guidelines.ResultsIn patients with cystic neoplasms of the pancreas undergoing DAB, results of cytological examination were non-informative in certain cases. However, analysis of CEA levels in the pancreatic juice and bile mixture always demonstrated strong concordance with the degree of dysplasia. In some instances, elevated CEA values facilitated the adoption of a more aggressive treatment strategy, leading to the detection of carcinoma. Conversely, low CEA levels prompted the decision to opt for observation rather than radical surgery in other cases.ConclusionDiagnosing precancerous transformations of the pancreas remains a challenging task, characterized by a notable rate of false-positive or false-negative conclusions. The DAB method offers a promising solution, seamlessly integrating into routine clinical practice and offering supplementary data to enhance the verification of pancreatic cancer. Citation Format: Aleksei Kashintsev, Vitali Proutski. Duodenal aspiration biopsy in diagnosis of pancreatic neoplasms [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr B015.