Management and outcome of HER2-positive breast cancer treated with and without adjuvant trastuzumab: The Imperial College London experience.

650 Background: Adjuvant trastuzumab (AT) is the standard of care in the management of HER2-positive breast cancer (BC) treated with chemotherapy (CT). Controversy remains regarding AT in low-risk disease and older patients. Little data is available outside large well controlled clinical trials with regard to the usage, efficacy and toxicity of AT, and no prospective data is available on the outcome of untreated HER2-positive patients diagnosed in the AT era. Methods: All cases of early invasive HER2-postive BC diagnosed at Imperial College London (ICL) between 2006-2008 were identified. In addition, patients referred for AT but who did not undergo breast surgery at ICL were included in analysis of efficacy. Results: Local HER-positivity rate for early invasive BC was 13.2% (128/1194), with 53.8% (85/158) receiving AT. Main reason for omission of AT was low-risk disease (32.7%). 128 cases (85 local and 43 referred) received AT. Median tim to AT after completion of radiotherapy (RT) was 28 days (range 2-18...