A retrospective, observational, not EPA, multicenter study to evaluate the Clinical Benefit of Trastuzumab in Combination With Lapatinib in Metastatic Breast Cancer HER2 Positive Patients Who Has Been Previously Treated With Trastuzumab and/or Lapatinib between January 2005 and December 2011

Inclusion Criteria:

• Confirmed diagnosis of metastatic breast cancer HER2-positive phenotype (confirmed by IHC 3 + or FISH positive)
• Older than 18 years
• Progressed to at least one prior treatment line for MBC with trastuzumab and / or lapatinib, either as monotherapy or in combination with chemotherapy or hormonal therapy schemes
• Having the patient's complete medical history that contains all lines antiHER2 therapy treatment
• Being a patient who initiated the combination of trastuzumab and lapatinib between January 2005 and December 2011
• Inform the patient and get the signature of the informed consent

Exclusion Criteria:

• Not having phenotypic classification of the tumor by IHC or FISH test for HER2
• Being a patient with HER2-negative phenotype(FISH negative or IHC in range [0-2 +] without FISH)
• Being a patient who received the trastuzumab and/or lapatinib treatment (TL) in combination with chemotherapy
• Being a patient who, since January 2012, began TL therapy for metastatic disease.

Patients with HER2 positive metastatic breast cancer who progressed to antiHER2 therapy with trastuzumab and / or lapatinib for the metastasic disease and that between January 2005 and December 2011, began treatment with the combination of trastuzumab and lapatinib (TL).