Predictive value of contrast enhancement on computed tomography for the responses to oxaliplatin-based chemotherapy with bevacizumab for hepatic metastases from colorectal cancer.

Abstract

e14105 Background: The addition of bevacizumab (Bev) to chemotherapy is associated with improved survival by anti-angiogenic mechanism in colorectal cancer (CRC). Therefore, the antitumor effect of Bev may correlate with the degree of the contrast-enhancement (CE) of targets reflecting tumor microvessels on the computed tomography (CT). The purpose of this study was to determine whether responses to chemotherapy with bevacizumab correlated with the degree of CE of hepatic metastatic lesions of colorectal cancer (CRC). Methods: Thirty one patients with hepatic metastases from CRC who underwent at least three course of mFOLFOX6 or XELOX therapy as the first-line chemotherapy between September 2006 and April 2010 were analyzed retrospectively. The patients were divided into two groups with or without Bev (17 in the Bev group and 14 in the non-Bev group). CT scans were performed during the late arterial phase following intravenous injection with a nonionic contrast medium at a dose of 600 mgI/kg, using a multi detector CT. Using an imaging control system, the diameter and mean CT values of metastatic lesions before chemotherapy were determined in each patient. The degree of CE was evaluated by the ratio of the CT value of hepatic metastases in the late arterial phase by in the noncontrast phase (i.e., CE ratio), whereby the patients were divided into the high or low CE group by the median CE ratio. Results: There was significant correlation between the CE ratio and the tumor shrinkage rate in the Bev group (R2 =0.3817, p=0.0082), whereas no such relationship was noted in the non-Bev group. In the high CE group (n=16), the tumor shrinkage rate increased to 35.9% in the Bev group from 8.6% in the non-Bev group (p=0.0716). In the low CE group, however, no significant difference was noted. Conclusions: The present study demonstrated the correlation between the CE ration and the tumor shrinkage in patients treated with Bev. The results suggest that the CE ratio on CT scanning in hepatic metastatic lesion can be a predictive value for the response to chemotherapy with Bev, although generalization of the CE ratio and the prospective study should be need.