Retrospective analysis of pathologic response in colorectal cancer liver-only metastases following treatment with bevacizumab.

Abstract

674 Background: Recent reports have shown that pathological response predicts for better outcome (overall survival) following preoperative chemotherapy and surgical resection of colorectal cancer (CRC) liver-only metastases. The aim of this retrospective analysis was to evaluate the effect of adding bevacizumab to standard chemotherapy on pathological response in patients with CRC liver only metastases. Methods: Patients with stage IV CRC with liver metastases who received neoadjuvant chemotherapy (oxaliplatin-or irinotecan-based) at two Spanish centres were analysed retrospectively. Pathological response was evaluated as follows: complete pathological response (cPR), PR1 (25% of residual tumour), PR2 (25–50% of residual tumour), PR3 (>50% of residual tumour). cPR or PR1 was considered to be a good response, and PR2 or PR3 a poor response. Results: A total of 81 patients were evaluated. Of these, 43 received chemotherapy alone and 38 received chemotherapy plus bevacizumab. Baseline characteristics were as follows: median age 61.0 years (range 43.0–80.0 years); male/female (67%/33%); tumour location – colon (69%) / rectum (31%); hepatic metastases – synchronous (74%) / metachronous (26%); In terms of pathological response, 58% of patients receiving bevacizumab had a good response (cPR + PR1) compared with 28% of those receiving chemotherapy alone. At the end of the analysis, 68% of patients were still alive. Conclusions: Adding bevacizumab to oxaliplatin-based chemotherapy in the neoadjuvant setting improves the pathological response of liver metastases in patients with stage IV CRC. These findings indicate that pathological response might be a good indicator of outcome for patients receiving bevacizumab in the neoadjuvant setting.