Impact of K-ras status on the effects of EGFR-targeted monoclonal antibody (MAb) therapy in advanced colorectal cancer (ACRC): A systematic review and meta-analysis of randomized controlled trials (RCTs) - Vale, C; Tierney, J; Meade, A; Fisher, D; Kaplan, R; Adams, R; Maughan, T; Parmar, M (2009)