Eligible patients ( @ years , left ventricular ejection fraction @ % , Eastern Cooperative Oncology Group performance status @-@ ) with progressive HER@-positive advanced breast cancer who had received two or more HER@-directed regimens in the advanced setting , including trastuzumab and lapatinib , and previous taxane therapy in any setting , were randomly assigned ( in a @:@ ratio ) to trastuzumab emtansine ( @ mg/kg intravenously every @ days ) or physician 's choice using a permuted block randomisation scheme by an interactive voice and web response system .