The Long-HER study: Clinical and molecular analysis of advanced HER2+ breast cancer treated with trastuzumab and associated to long-term survival.

608 Background: Some patients with advanced HER2+ breast cancer survive in the long-term after receiving trastuzumab-based therapy. Long-HER study was an observational, multicenter study that compared long-term survivors and a control group from the clinical and molecular point of view. Methods: Patients with metastatic HER2+ breast cancer that had been treated with trastuzumab-based therapy and had an objective response or stable disease for at least 3 years were included. A control group having a progression in the first year of therapy was selected for comparison (similar first-line therapy). A microarray platform was used to assess whole genome expression analysis in paraffin-embedded samples. Differential expression, ontology and analysis of metabolic pathways were performed. Results: 103 patients were registered, 71 of who had a long-term complete remission. Only 5 of these patients had received trastuzumab in the adjuvant setting: this was the only clinical factor associated to long-term survival. ...