Combination Gemcitabine, Carboplatin With or Without Trastuzumab in Patients With Metastatic Breast Cancer

Inclusion Criteria: To be included in this study, you must meet the following criteria: * Locally advanced or metastatic breast cancer * Measurable disease as per RECIST criteria * No prior chemotherapy in the metastatic breast setting * Prior chemotherapy and/or hormonal therapy for early stage breast cancer * Adjuvant Herceptin is allowed * Prior radiation therapy in either the metastatic or early stage setting * Patients may have received any number of hormonal therapies * Age \>18 years * Only women are eligible for the study * Able to perform activities of daily living with minimal assistance * Normal organ and bone marrow function * Patients who will be receiving Trastuzumab must have normal heart function * Sign a written informed consent document Exclusion Criteria: You cannot participate in this study if any of the following apply to you: * Received prior chemotherapy for metastatic breast cancer * Known leptomeningeal carcinomatosis * Uncontrolled brain metastasis * Uncontrolled intercurrent illness * Pregnant or lactating * History of other non-breast cancer malignancy * Received prior chemotherapy for early stage breast cancer within 6 months Please note: There are additional inclusion/exclusion criteria. The study center will determine if you meet all of the criteria. If you do not qualify for the trial, study personnel will explain the reasons. If you do qualify, study personnel will explain the trial in detail and answer any questions you may have.