e15133 Background: The role of palliative resection of the primary tumour in patients who present with metastatic colorectal cancer (mCRC) is unclear. Most recently bevacizumab has been used as first line treatment for mCRC showing improvement in survival with a slight increase in the risk of bleeding and rarely gastrointestinal (GI) perforation. These side effects would cause concern in patients with unresected colorectal cancers (CRC). Methods: Retrospective analysis of twelve patients treated straightaway by chemotherapy (CT) and bevacizumab without primary tumour resection, between January 2007 and August 2008. The aim of the study was to evaluate the rate of complications related to the unresected colorectal tumour and to determine the safety of bevacizumab use in this situation. All of these patients had none or minimal symptoms related to the primary tumour. Results: Mean age 54.6 years (range 28–75), 5 males and 7 females, all patients ECOG 0. The sites of the primary lesion were the rectum in 8 patients (66.6%), the left sigmoid colon in 3 (25%), and the transverse colon in 1 (8.3%). Eight patients (66.6%) presented with rectal bleeding at diagnosis (mild). The mean interval between diagnosis and start of CT was 40,8 days (range 6–125). The total number of bevacizumab cycles was 151 (mean 12,5 cycles, range 4–37). First line CT was FOLFOX-6 in 66% and FOLFIRI in 33% of patients. Only 3 patients (25%) developed low GI bleeding, all grade 1, without bevacizumab interruption. None of them developed intestinal perforation or obstruction. Two patients (16.6%) developed grade 1 epistaxis and 1 (8.3%) grade 2 hypertension. No other complications were observed in a mean follow up of 9.3 months. Conclusions: Our data show that upfront chemotherapy with bevacizumab in patients with unresected primary CRC and synchronous metastases is safe. No major complications related to the primary tumour were observed. Although our data comes from a limited number of patients there is a lack of prospective controlled trials in the literature on this topic. Therefore, in select cases, a non-operative management of asymptomatic or minimal symptomatic mCRC could be advised, even with the use of anti-angiogenic therapy. No significant financial relationships to disclose.