Prognostic Significance of Tumor Regression After Preoperative Chemoradiotherapy for Rectal Cancer

Purpose We assessed the impact of tumor regression grading (TRG) and its value in correlation to established prognostic factors in a cohort of rectal carcinoma patients treated by preoperative chemoradiotherapy (CRT). Patients and Methods TRG was evaluated on surgical specimens of 385 patients treated within the preoperative CRT arm of the CAO/ARO/AIO-94 trial: 50.4 Gy was delivered, fluorouracil was given in the first and fifth week, and surgery was performed 6 weeks thereafter. TRG was determined by the amount of viable tumor versus fibrosis, ranging from TRG 4 when no viable tumor cells were detected, to TRG 0 when fibrosis was completely absent. TRG 3 was defined as regression more than 50% with fibrosis outgrowing the tumor mass, TRG 2 was defined as regression less than 50%, and TRG 1 was defined basically as a morphologically unaltered tumor mass. We performed an initially unplanned, hypothesis-generating analysis with respect to the prognostic value of this TRG system. Results TRG 4, 3, 2, 1, 0 wa...