Trastuzumab treatment in patients with advanced breast cancer (ABC) confined to locoregional and skeletal sites: Results from a large noninterventional study.

640 Background: In a prospective observation study routine trastuzumab (T) treatment in HER2+ ABC was evaluated in a total of 1,687 patients (pts) since 2001. This large number allows the subgroup analysis of patients with the involvement of specific sites. Methods: Information on extent of advanced disease was available in 1,674 pts (99%) with HER2 overexpressing ABC. Pts were either pre-treated (39%) or naïve to palliative chemotherapy (CT). The following subgroups and their characteristics were analysed: I: locally ABC only; II: bone metastases allowing for concomitant local tumour; III: other. Results: Locally advanced lesions were found to be the sole BC manifestation in 145 pts (8.7%…