Relevant issues in tumor regression grading of histopathological response to neoadjuvant treatment in adenocarcinomas of the esophagus and gastroesophageal junction.

Multimodality treatment combining surgery and oncologic treatment has become widely applied in curative treatment of esophageal and gastroesophageal junction adenocarcinoma. There is a need for a standardized tumor regression grade scoring system for clinically relevant effects of neoadjuvant treatment effects. There are numerous tumor regression grading systems in use and there is no international standardization. This review has found nine different international systems currently in use. These systems all differ in detail, which inhibits valid comparisons of results between studies. Tumor regression grading in esophageal and gastroesophageal junction adenocarcinoma needs to be improved and standardized. To achieve this goal, we have invited a significant group of international esophageal and gastroesophageal junction adenocarcinoma pathology experts to perform a structured review in the form of a Delphi process. The aims of the Delphi include specifying the details for the disposal of the surgical specimen and defining the details of, and the reporting from, the agreed histological tumor regression grade system including resected lymph nodes. The second step will be to perform a validation study of the agreed tumor regression grading system to ensure a scientifically robust inter- and intra-observer variability and to incorporate the consented tumor regression grading system in clinical studies to assess its predictive and prognostic role in treatment of esophageal and gastroesophageal junction adenocarcinomas. The ultimate aim of the project is to improve survival in esophageal and gastroesophageal adenocarcinoma by increasing the quality of tumor regression grading, which is a key component in treatment evaluation and future studies of individualized treatment of esophageal cancer.