Benefit of Adding Trastuzumab to Second Line Chemotherapy in Breast Cancer Patients Previously Treated With Trastuzumab

Inclusion Criteria: * Written informed consent. * Women older than 18 years old. * HER2 positive breast cancer with histological diagnoses. * Non-operable locally advanced or metastatic disease, previously treated with trastuzumab and taxanes. * Measurable or non-measurable disease as per Response Evaluation Criteria in Solid Tumors (RECIST). * Disease progression during or after treatment with trastuzumab and taxanes. * Maximum of 1 previous chemotherapy line for advanced or metastatic disease. * Previous radiotherapy is allowed if radiated area is not the only documented lesion. * At least 4 weeks since the last administration of antineoplastic treatment and all toxicities resolved. * Performance status Eastern Cooperative Oncology Group (ECOG) \>=2. * Life expectancy of at least 12 weeks. * Left Ventricular Ejection Fraction (LVEF) evaluation (\>=50%) in previous 4 weeks. * Hematology: * neutrophils \>=1.5 x 10e9/l; * platelets \>= 100 x 10e9/l; * hemoglobin \>= 10 mg/dl * Hepatic function: * total bilirubin \<= 1.5 x under normal limit (UNL); * Aspartate aminotransferase (SGOT) and Alanine aminotransferase (SGPT) and alkaline phosphatase \<= 2.5 x UNL, or \<=5 x UNL if hepatic lesions present * Renal function: * creatinine \<= 175 µmol/l (2 mg/dl); * creatinine clearance \>= 60 ml/min. * Patients able to comply with treatment and follow-up. * Negative pregnancy test in the previous 14 days. Adequate contraceptive method during treatment and up to 3 month…