[Grading of tumor regression of gastrointestinal carcinomas after neoadjuvant therapy].

Pre- or perioperative chemo- or radiochemotherapy and subsequent resection is the standard therapy for locally advanced esophageal, gastric, and rectal cancer. A tumor regression grading (TRG; also tumor regression grade) categorizes the extent of the regressive changes after a neoadjuvant treatment. There are several TRG systems for gastrointestinal carcinomas that relate either to the extent of the therapy-induced fibrosis in relation to the residual tumor or the estimated proportion of the residual tumor in the area of the former tumor area. An ideal TRG system shows significant interobserver agreement and offers relevant prognostic information - in most cases a complete or almost complete regression after neoadjuvant therapy is associated with an improved prognosis. In this review, the most commonly used TRG systems for gastrointestinal carcinomas are presented and discussed. In addition, current issues such as the standardization of TRG and the subject of regression in lymph node metastases in the context of a TRG system are discussed.