Regression grading in post neoadjuvant treated pancreatic cancer

Neoadjuvant chemoradiation (NCRT) is emerging as an important treatment modality in borderline resectable pancreatic ductal adenocarcinoma (PDAC) in an attempt to reduce tumour stage and improve resectability. Currently, there are several systems utilised to grade tumour regression in PDAC; the most widely used of these are the Evans, MD Anderson (MDA) and College of American Pathologists (CAP) systems. There is also significant institutional variation in handling and reporting tumour regression in post treated PDAC. As a result, there is a need for a standardised and reproducible method of handling and assessing these specimens in routine practice. This review aims to provide an overview of histological grading in neoadjuvant treated pancreatic cancer, focussing on the different regression grading systems with particular attention to the three most frequently recommended and used systems. In addition, we briefly outline the handling of post-treated pancreatic resections and the spectrum of histological features encountered in these specimens.