588 Background: Bevacizumab (BV) is a recombinant, humanized monoclonal antibody against vascular endothelial growth factor. Used in combination with chemotherapy, BV has been shown to improve survival in both first- and second-line treatment for metastatic colorectal cancer (mCRC). However, it was reported that addition of BV to FOLFOX conferred only little survival benefit (Saltz et al. JCO2008). The aim of this study was to assess the efficacy of addition of BV to FOLFOX in first-line treatment for patients with mCRC. Methods: Bevacizumab was approved for mCRC in July 2007 in Japan. This study was conducted at a single institution and comprised 217 consecutive patients receiving first-line treatment for mCRC between 2005 and 2009. The primary objective was to compare survival benefit in patients treated with FOLFOX4 (FF) between 2005 and 2007 with that in patients receiving FOLFOX4+BV 5 mg/kg (FF+BV) between 2007 and 2009. Results: Total number of patients in the FF and FF+BV groups was 132 and 85, respectively. Characteristics of patients were as follows (FF vs. FF+B): median age, 62 yrs (range 28-76 yrs) vs. 60 yrs (range16-74 yrs); ECOG PS0, 98.8% vs. 81.8%; and median follow-up time, 20.8 months vs. 24.4 months. Median progression-free survival (PFS) in the FF and FF+BV groups was 10 months (95% CI, 8.7-11.3) and 17 months (95% CI, 10.2-14.1), while median overall survival (OS) was 21 months (95% CI, 17.9-24.1) and not reached, respectively. Response rate was 46% (95% CI, 37- 54) in FF, and 62% (95% CI, 51-73) in FF+BV. Addition of BV to FOLFOX4 significantly improved PFS (p=0.002) and OS (p<0.001). Conclusions: The additive effect of BV for first-line FOLFOX was reconfirmed. These data indicate potential survival benefits from the addition of BV to FOLFOX in first-line treatment of mCRC. In addition, PFS may be a sensitive indicator of outcome prior to post-treatment. No significant financial relationships to disclose.