Morphologic Changes Associated with Neoadjuvant-Treated Pancreatic Ductal Adenocarcinoma and Comparison of Two Tumor Regression Grading Systems.

Abstract Pancreatic ductal adenocarcinoma is aggressive, with an overall five-year survival rate of 9%, and few patients are candidates for pancreatectomy at presentation. The role of neoadjuvant therapy (NAT) is evolving, especially for high-risk potentially resectable tumors. Due to the increasing number of NAT resection specimens, we aim to characterize the histologic changes associated with NAT, and to compare two tumor regression grading schemes. 118 resections for pancreatic ductal adenocarcinoma were selected from the cases between 2011-2018, 59 not treated and 59 treated with NAT. All HE while the modified Ryan score did not.