Impact of primary tumour location on efficacy of bevacizumab plus chemotherapy in metastatic colorectal cancer

Background Two first-line (1L) bevacizumab trials showed the prognostic value of primary tumour location in metastatic colorectal cancer (mCRC). In this retrospective subgroup analysis, further analysis of the predictive effect of bevacizumab is presented. Methods Patients with sidedness information from two randomised phase III studies of bevacizumab + chemotherapy (CT) vs CT as 1L mCRC treatment were analysed retrospectively. Results Sidedness was determined in 1590 (27% right and 73% left) of 2214 patients. Progression-free survival was improved with bevacizumab + CT vs CT in right-sided (HR = 0.75; 95% CI 0.61, 0.93; p = 0.008) and left-sided (HR = 0.76; 95% CI 0.67, 0.86; p