Histological tumor regression after preoperative chemotherapy for colorectal liver metastases: Correlations with radiological response and prognosis.

Abstract

609 Background: The purpose of this study was to characterize histological tumor regression grade (TRG) to colorectal liver metastases (CLM) treated with preoperative chemotherapy followed by liver surgery, and to evaluate whether TRG correlates with radiological response and prognosis. Methods: This study included 30 patients with CLM treated by surgical resection after preoperative chemotherapy with oxaliplatin- or irrinotecan-based regimens with or without molecular target agents. TRG was determined by the amount of fibrosis and necrosis replaced from tumor cells, ranging TRG 0 (0%), 1 (1-24%), 2 (25-50%), 3 (51-99%), and 4 (100%). Results: TRG 0, 1, 2, 3, and 4 were observed in 0%, 6.7%, 10.0%, 66.7%, and 16.6% of the patients, respectively. There were no relations between TRG and regimen, including molecular target agents. As shown in the table, radiological response was not significantly correlated with TRG. Patients with histological major response (TRG 3+4) had better prognosis (MST; TRG 1+2 vs. 3+4: 20.0 vs. 50 months, P= 0.007), and a multivariate analysis identified histological major response as an independent good prognostic factor. Conclusions: In this analysis, histological TRG predicted survival after preoperative chemotherapy and resection for CLM. Preoperative radiological response could not evaluate TRG. [Table: see text]