Study of Gemcitabine and Herceptin Versus Xeloda and Herceptin in HER-2 (+) Metastatic Breast Cancer Patients

Inclusion Criteria: * Informed consent * Histologically confirmed metastatic breast adenocarcinoma (stage IV) without any prior chemotherapy received * HER-2 overexpression 2+ or 3+ using IHC or FISH + * Measurable disease * At least one prior chemotherapy regimen * Not in a prior irradiation field * No patients with brain metastatic disease who has not been irradiated or uncontrolled brain metastatic disease after irradiation * No more than 25% of myeloproductive bone marrow irradiated. More than 4 weeks since prior radiotherapy and recovered * Age 18 - 75 year old * Performance status (WHO) 0-2 * Life expectancy more than 12 weeks * Absolute neutrophil count \> 1500/mm\^3, platelet count \> 100000/mm\^3, hemoglobin \> 9 gr/mm\^3) * Adequate liver (bilirubin \< 2 mg/dL, SGOT/SGPT \< 2 times upper limit of normal, ALP \< 3 times upper limit of normal, creatinine \< 1.5 upper limit of normal * Adequate cardiac function (LVEF \> 50%) Exclusion Criteria: * Pregnant or nursing * Positive pregnancy test * Concurrent agents ketoconazole, macrolide antibiotics, zidovudine which may induce P-450 cytochrome * Motor or sensory neuropathy \> grade 1 according to NCIC toxicity criteria * History of allergic reaction attributed to docetaxel * Psychiatric illness or social situation that would preclude study compliance * Other concurrent uncontrolled illness * Other invasive malignancy within the past 5 years except cured basal cell skin carcinoma and cervical carcinoma in situ