Lessons learned from hepatocellular carcinoma may cause a paradigm shift in intraductal papillary mucinous neoplasms: a narrative review and discussion of conceptual similarities in tumor progression and recurrence

Although the natural history of recurrence/progression in patients with intraductal papillary mucinous neoplasms (IPMN) of the pancreas has not been studied thoroughly, the three principal mechanisms have been identified: (a) presence of residual disease at the transection margin, (b) presence of intraductal/intraparenchymal metastases and (c) development of new primary lesions. Mechanisms (a) and (b) result in metastatic lesions that are genetically related to the primary, while new primary lesions (mechanism c) are genetically distinct. Interestingly, recurrence/progression in IPMN displays conceptual parallels with the well-established paradigm of disease recurrence in patients with hepatocellular carcinoma (HCC). Specifically, patients with HCC may also develop recurrent tumors due to microscopic residual disease/intrahepatic metastasis which are genetically similar to the primary while the development of genetically unrelated, de novo HCC after curative-intent resection is also common. The latter has been attributed to the presence of a widespread genetic abnormality ("field defect") in the liver (ie, cirrhosis). Given the conceptual similarities between IPMN and HCC, a pancreatic "field defect"may also be hypothesized to exist. This review does not suggest that HCC and IPMN have identical pathogeneses, but rather that they have conceptual similarities in tumor recurrence/progression; thus, lessons learned from HCC could be applied to IPMN research and subsequent management. Conceptual similarities in tumor progression and recurrence may also be observed between IPMN and other malignancies. However, HCC was selected because it is well studied and can serve as a paradigm.