An Open-Label, Randomized, Multicenter Phase III Study in Patients With HER2-Positive Metastatic Breast Cancer Responding to First Line Treatment With Intravenous Trastuzumab for at Least 3 Years and Investigating Patient Preference for Subcutaneous Trastuzumab

This open-label, randomized, multicenter study will evaluate participant preference for subcutaneous (SC) versus intravenous (IV) trastuzumab (Herceptin) in participants with HER2-positive metastatic breast cancer responding to first-line treatment with IV trastuzumab for at least 3 years. Participants will be randomized to receive either 3 cycles (cycle length = 21 days) of trastuzumab SC followed by 3 cycles of trastuzumab IV or 3 cycles of trastuzumab IV followed by 3 cycles of trastuzumab SC. All participants will receive trastuzumab SC for Cycles 7 to 18. Anticipated time on study treatment is 1 year or until disease progression or inacceptable toxicity occurs, whichever comes first.