Statement: Completely disabled patients below the age of 20, totally confined to bed or chair and unable to carry on any selfcare are eligible for the primary trial but excluded from the secondary trial.
Primary_evidence: Inclusion Criteria:   Women  20 years   Histologically or cytologically confirmed diagnosis of adenocarcinoma originating in the breast Exclusion Criteria:   Number of prior chemotherapy lines of treatment in the metastatic setting 3
Secondary_evidence: Inclusion Criteria:   Adult participants >/=18 years of age   HER2-positive breast cancer   Histologically or cytologically confirmed adenocarcinoma of the breast with locally recurrent or metastatic disease, and be a candidate for chemotherapy. Participants with locally advanced disease must have recurrent or progressive disease, which must not be amenable to resection with curative intent.   Participants must have measurable and/or non-measurable disease which must be evaluable per Response Evaluation Criteria in Solid Tumors (RECIST) 1.1   Eastern Cooperative Oncology Group (ECOG) Performance Status 0 or 1   Adequate organ function as determined by laboratory results Exclusion Criteria:   History of prior (or any) chemotherapy for metastatic breast cancer or recurrent locally advanced disease   An interval of <6 months from the last dose of vinca-alkaloid or taxane cytotoxic chemotherapy until the time of metastatic diagnosis   Hormone therapy <7 days prior to randomization   Trastuzumab therapy and/or lapatinib (neo- or adjuvant setting) <21 days prior to randomization   Prior trastuzumab emtansine or pertuzumab therapy