Prognostic role of high-grade tumor budding in pancreatic ductal adenocarcinoma: A systematic review and meta-analysis with a focus on epithelial to mesenchymal transition

This study aims at clarifying the prognostic role of high-grade tumor budding (TB) in pancreatic ductal adenocarcinoma (PDAC) with the first systematic review and meta-analysis on this topic. Furthermore, we analyzed with a systematic review the relationship between TB and a recently suggested TB-associated mechanism: the epithelial to mesenchymal transition (EMT). Analyzing a total of 613 patients, 251 of them (40.9%) with high grade-TB, we found an increased risk of all-cause mortality (RR, 1.46; 95% CI, 1.13-1.88, p = 0.004; HR, 2.65; 95% CI, 1.79-3.91; p < 0.0001) and of recurrence (RR, 1.61; 95% CI, 1.05-2.47, p = 0.03) for PDAC patients with high-grade TB. Moreover, we found that EMT is a central process in determining the presence of TB in PDAC. Thanks to this meta-analysis, we demonstrate the potential clinical significance of high-grade TB for prognostic stratification of PDAC. TB also shows a clear association with the process of EMT. Based on the results of the present study, TB should be conveyed in pathology reports and taken into account by future oncologic staging systems. © 2019 by the authors. Licensee MDPI, Basel, Switzerland.