Outcome of HER2-Positive (HER2+) Metastatic Breast Cancer Patients (MBC) Treated with Trastuzumab (T): An Institutional Based Review.

Background: HER2+ status is associated with poor prognosis, high incidence of visceral and brain metastasis. However the addition of trastuzumab to chemotherapy (CT) significantly improves survival in early and advanced breast cancer. The purpose of this retrospective study was to explore the pattern of outcome in a cohort of MBC patients treated with T-based chemotherapy in a single institution. T was approved in Europe in 2000 and in 2001 all pts had access to T according HER2+ status. Methods: Women with de novo or recurrent breast cancer treated with trastuzumab at Institut Curie between 2001 and 2006 with HER2+ status (IHC 3+ or FISH +) were identified from the Institut Curie database. Disease was classified in two groups: patients who received T upfront and those who received T after one or several CT regimens. Overall survival (OS) was defined as the time from the date of the first metastasis to the date of death or last follow-up and was estimated using the Kaplan-Meier product method. Results: The final analysis included 244 patients. Median age was 53.4 yrs (29-80). Median time from primary and first metastasis was 22 mths (0-238). Visceral metastasis were present in 153 pts (63%) and 125 pts (51%) presented multiple sites. One hundred pts (42%) developed brain metastasis during the course of disease. One hundred and sixty five pts (68%) received T as first line, 79 pts (32%) after a median of one line of CT (median 1, range 1-5). One hundred and twenty four pts (52%) received more than 3 regimens. The median overall survival was 53 mths (4-113), similar in both groups. However there is a major bias: pts with very aggressive disease not treated upfront with T not have not been offered delayed T and don9t appear in the analyzed population. Patients who developed brain metastasis had a median survival of 41 mths (11-90). Complete characteristics of pts will be presented. Conclusions: The introduction of T has altered the natural history of HER2+disease. Even outside a clinical trial, our results show that the addition of T to CT improves the prognosis of MBC patients with HER2+ disease. Prolongation of T after progression with other CT appears beneficial, even in pts with a high disease burden. The high incidence of brain metastases remains an issue in such a population. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 5107.