Phase III to Evaluate Patient´s Preference of Subcutaneous Trastuzumab vs Intravenous in HER2+ Advanced Breast Cancer

Approximately 195 patients will be included to receive subcutaneous trastuzumab a fixed dose of 600 mg every 3 weeks for 4 cycles (2 administered from the injection of a vial with a syringe and 2 with the injection device). Following administration of these four cycles, the patient will decide whether or not to continue with the subcutaneous formulation of trastuzumab every 3 weeks until progression (out of the study). Since the randomization in the study until the start with subcutaneous trastuzumab, patients will receive a treatment cycle of intravenous trastuzumab as usual. Main objective: Proportion of patients indicate a preference for the use of subcutaneous vs intravenous trastuzumab. This principal primary objective will be analyzed with the answers to questionnaire of experiences and preferences of the patients (Principal endpoint) The duration of the study has been estimated after 34 months.