Tumor regression grading after neoadjuvant treatment of esophageal and gastroesophageal junction adenocarcinoma - Results of an international Delphi consensus survey

Abstract Background and aim Complete histopathologic tumor regression after neoadjuvant treatment is a well-known prognostic factor for survival among patients with adenocarcinomas of the esophagus and gastroesophageal junction. The aim of this international Delphi survey was to reach a consensus regarding the most useful tumor regression system that could represent an international standard for histopathologic tumor regression grading of gastroesophageal carcinomas. Methods Fifteen expert pathologists participated in the online survey. The initial questionnaire contained of 43 statements that addressed the following topics: (1) specimen processing, (2) gross examination, (3) cross sectioning, (4) staining, (5) Barrett’s esophagus, (6) tumor regression grading systems and (7) grading tumor regression in lymph node deposits. Participants rated the items using a 5-point Likert style scale and were encouraged to write comments for each statement. Results The expert panel recommended a 4-tiered tumor regression system for assessing the primary tumor: Grade 1: No residual tumor (complete histopathologic tumor regression), Grade 2: less than 10% residual tumor (near complete regression), Grade 3: 10% to 50% residual tumor (partial regression), Grade 4: Greater than 50% residual tumor (minimal/no regression), combined with a 3-tiered system for grading therapeutic response in metastatic lymph nodes deposits: Grade a: no residual tumor (complete histopathologic tumor regression), Grade b: partial regression (tumor cells and fibrosis), Grade c: no regression (no sign of tumor response). Conclusion This tumor regression grading system can be recommended as an international standard for histopathologic tumor regression grading in esophageal and gastroesophageal junction adenocarcinoma.