Clinical implications of the molecular characterization of intraductal papillary mucinous neoplasms of the pancreas

Intraductal papillary mucinous neoplasm (IPMN) is a pre-malignant, mucin-producing epithelial lesion arising from pancreatic ducts. Observational reports define IPMN behavior as ranging from indolent, asymptomatic lesions to dysplasia that sometimes degenerate into pancreatic adenocarcinoma. The goal of IPMN management is riskreducing surgery for high-risk cysts and observation of the remainder. Discriminating highfrom low-risk IPMN disease still relies on imaging and clinical cyst characteristics. Here, we review the accepted classification of IPMN including the most common histological subtypes, their clinical features, and currently-accepted high-risk phenotypes. We then deeply examine the known molecular landscape of IPMN, which has largely been derived from post-resection analysis. This includes those gene variants unique to IPMN, chiefly GNAS and RNF43, but also examines the overlap between IPMN and conventional pancreatic adenocarcinoma. Utilizing molecular markers in the clinical setting relies on endoscopically-obtained cyst fluid and presumes that it accurately represents the molecular characteristics of the cystic epithelium. We synthesize existing data on mutational analysis from IPMN cyst fluid and consider the benefits and proper role of current commercially-available cyst fluid molecular analysis kits. We conclude that carefully interpreted molecular analysis of resected IPMN tissue reveals insights into its biology and natural history while cyst fluid analysis offers prognostication and data to guide treatment decisions. However, knowledge gaps remain, especially in characterizing IPMN molecular heterogeneity, time to progression, and correlating cyst fluid genotype data with surveillance strategies. As such, substantial additional research is required before the promise of true molecular guidance of IPMN management can be realized. Page 2 of Peters et al. J Cancer Metastasis Treat 2021;7:31 https://dx.doi.org/10.20517/2394-4722.2021.67 18