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

Inclusion Criteria: * Woman, 18 years old or upper. * Patient with advanced breast cancer with human epidermal growth factor receptor 2 (HER 2) positive histologically confirmed. The criteria for positivity HER 2 are: 1. immuno-histochemistry (IHC) 3+ (\>10% of tumor cells with complete and intense membrane staining) 2. IHC 2+ with fluorescent in situ hybridization (FISH) / Chromogenic in situ hybridization (CISH) / silver-enhanced in situ hybridization (SISH) + for HER 2 amplification (\*) 3. FISH / CISH / SISH + for HER 2 amplification (\*) (\*) Defined as the ratio of copies of HER 2/neu and copies of centromere of chromosome 17 (CEP17)\> 2.2, or a number of copies of HER 2/neu\> 6, as per local laboratory criteria. * Patient receiving trastuzumab with or without chemotherapy or hormonal therapy for at least 4 months. * No evidence of disease progression (clinical and / or radiological) for at least 4 months before inclusion in the study and with a life expectancy of at least 3 months. * Adequate performance status: Eastern Cooperative Oncology Group (ECOG) \<2. * Adequate bone marrow function, liver and kidney * Proper cardiac function (LVEF within normal limits the center, measured by echocardiography or MUGA). * The patient must have been informed of the study and must sign and date informed consent document for entry into the trial. * The patient must be willing and able to comply with study procedures and be available to answer the study questionnaires. Exclusion Criteria: * Patients with no advanced breast cancer. * Breast cancer patients with tumors HER 2-negative. * The patient has another active malignancy other than breast adenocarcinoma; are excluded the non-melanoma skin cancer or any other properly treated in situ neoplasia. Patients with a history of malignancy, if they bear\> 5 years without evidence of disease could be included. * The patient has uncontrolled brain metastases. * Concomitant administration, or in the 4 weeks prior to study entry, of other experimental treatment. * Known hypersensitivity to trastuzumab or to any of its components. * Patients with severe dyspnea at rest or requiring supplemental oxygen. * Heart disease or serious medical pathological prevent trastuzumab administration: documented history of congestive cardiac insufficiency (CCI), high-risk arrhythmias uncontrolled angina requiring medication, clinically significant valvular disease, history of myocardial infarction or evidence of transmural infarction on ECG or hypertension poorly controlled. * Presence of any concomitant serious systemic disease that is incompatible with the study (at the discretion of the investigator). * The patient is pregnant or lactating. Women of childbearing potential should undergo pregnancy testing blood or urine within 14 days prior to inclusion as institutional rules and use a non-hormonal contraceptive suitable: intrauterine device, barrier method (condom or diaphragm) also used in conjunction with spermicidal cream, total abstinence or surgical sterilization, during treatment with the study drugs and for 6 months following the end of treatment.