Main objective: To analyze the clinical and biological characteristics of patients with disseminated breast cancer HER2 + treated with trastuzumab that have achieved a complete remission, partial or stable disease for a period exceeding 3 years.

In addition, there will be a sub-genetic analysis of patients in whom there is availability a sample of primary tumor preserved in paraffin. This sub-analysis will not interfere with routine clinical practice, as the tumor samples based on which will be held on genetic profile, have been preserved in paraffin was extracted from the primary tumor to the patient.

SECONDARY OBJECTIVES:

• To determine the frequency of patients achieving partial response or stable disease for a period exceeding 3 years.
• Know the time to complete or partial remission or to achieve stabilization of the disease.
• Know the length of the complete or partial remission or time to disease stabilization of patients.
• Knowing the pattern of treatment that has achieved complete or partial remission or stabilization of disease and duration.
• Knowledge of overall survival.
• Knowing the toxicity of prolonged administration of trastuzumab.
• Identify the primary tumor genes HER-2 associated with such prolonged responses.

The source document will be in all cases the clinical history and in the case of patients selected for the sub-genetic analysis, the report resulting from it.

The study is carried out by filling a notebook of electronic data collection that gathers all available information contained in medical records.

The sub-genetic analysis will be performed at the Hospital de la Paz. Both, the processing of samples and conducting the analysis using qRT-PCR, will be performed in this hospital.

All data are stored, ensuring the confidentiality, security and authenticity .The forms must be reviewed by the monitor.

Once recorded the data, the database will be revised and monitored to submit those records in which there are inconsistencies or missing information . Following the closure of the database will be a report which will present the results of the analysis of the data.

Inclusion Criteria:

1. Women older than 18.
2. Patients with disseminated breast cancer with overexpression of HER-2 (IHC 3 + or FISH +).
3. Patients who have been treated with trastuzumab (Herceptin ®).
4. Complete remission, partial or stable disease for a period exceeding 3 years, except for exclusive cerebral progression.
5. Patients who have given their written informed consent.

Exclusion Criteria:

1- Patients with remission achieved with surgery or less than three months of treatment with trastuzumab.

Women with disseminated breast cancer, HER-2 3+ or FISH+.