Clinical significance of brain metastases occurrence in HER2 overexpressing metastatic breast cancer patients treated with trastuzumab

10593 Background: Recent data report that HER2 overexpressing metastatic breast cancer patients (HER+ MBC pts) treated with trastuzumab (T) have a high rate of Brain metastasis (BM). This study aimed to evaluate the prognostic significance of BM occurrence and the related clinical outcome in a specific patient population. Methods: All the HER+MBC patients treated with trastuzumab (with or without chemotherapy) between 09/1999 and 12/2004 were included in this study. Results: A total of forty three patients were enrolled into the study cohort. The median follow-up was 48 months (range, 11–166). Fifteen patients (35%) developped BM. The median interval from the the first MBC event to BM was 18 months (range, 1–65). In multivariate analysis; younger age was the only factor associated with BM occurrence (46 versus 57 years; p = 0.01). Patients with BM tend to have a longer median duration of response to T than patients without BM (16 months versus 13 months; p = 0.1). At the time of BM appearance, 6 of the 15 patients (40%) were still responding or had achieved extracranial stable disease while receiving trastuzumab. Twelve out of 15 (80%) pts received a whole-brain radiation therapy, and 8 pts continued to receive trastuzumab until extracranial disease progression. The median overall survival for patients diagnosed with BM was 10 months (range, 2–42). At three-year, there was no significant difference in overall survival rates between the two groups. The 3-YS was 63.5% and 66.7% for pts with or without BM, respectively; (p = 0.7). Conclusions: The BM occurrence in HER2+ MBC pts treated with Trastuzumab is not linked to tumour resistance, but likely related to the T inability to cross the blood-brain barrier. There is no impaired survival for these pts treated with effective and appropriate therapy. [Table: see text]