Pathologic Assessment and Staging Cancers of Digestive Organs in the Era of Neoadjuvant Therapy.

Neoadjuvant therapy is employed to downstage many locally advanced gastrointestinal and pancreatic cancers, reduce tumor burden, and improve survival. However, treatment also produces gross and histologic therapy-related changes, confounding pathologic assessment and causing challenges for pathologists. The accuracy of post-therapy pathologic staging and assessment relies on meticulous specimen examination and cognizance of therapy-induced gross and histologic changes. Tumor regression grading (TRG) provides additional prognostic information and is an invaluable adjunct to pathologic staging after neoadjuvant therapy. This review provides an overview of standardized gross and histologic assessment of rectal adenocarcinomas, upper gastrointestinal tract carcinomas and pancreatic adenocarcinomas.