Fulvestrant has proven effective in the treatment of hormone receptor positive metastatic breast cancer. The dose used in studies so far has been well tolerated and may be too low for optimal effectiveness. In this study, a higher dose will be used to see whether an improved outcome will result.

• Fulvestrant will be administered by intramuscular injection on day 1, day 15 and day 29 and then every 28 days thereafter.
• Participants will have a physical examination and blood work performed on each treatment date. After teh study treatment has been completed, the physical examinations will be done every three months for the first 2 years, every 6 months for years 2-5, and annually after 5 years.
• Participants may remain on study treatment until disease progression or until they experience serious side effects.

Inclusion Criteria:

• Female
• 18 years of age or older
• Histologically confirmed adenocarcinoma of the breast progressing local-regional or metastatic disease that is not considered amenable to curative treatment
• Evidence of hormone sensitivity of primary or secondary tumor tissue
• Postmenopausal as defined by criteria listed in protocol
• May have had adjuvant endocrine therapy if discontinued at least 12 months prior to inclusion. Subjects who have had minimal exposure to adjuvant or first line metastatic endocrine treatment during the 12 months prior to study enrollment can be eligible with overall PI and sponsor permission
• Prior trastuzumab and biologic therapy is allowed, but must be discontinued more than 2 weeks prior to inclusion
• Presence of measurable or evaluable, nonmeasurable, disease. Any x-rays and scans for assessment of measurable disease must be performed with 28 days prior to registration
• Eastern Cooperative Oncology Group (ECOG) performance status of 0,1 or 2

Exclusion Criteria:

• Presence of life-threatening metastatic disease
• Endocrine therapy the advanced disease setting
• Systemic chemotherapy, whether as adjuvant therapy or for advanced disease, within previous 4 weeks
• Trastuzumab or biologic therapy within previous 2 weeks
• Extensive radiation therapy within the last 2 weeks
• Prior adjuvant or neoadjuvant treatment with fulvestrant is not allowed
• Concomitant anticancer treatments
• Chronic bisphosphonates for hypercalcemia or prevention of bone metastases
• Subjects receiving long-term anticoagulant therapy with warfarin
• Estrogen replacement therapy within 6 months of trial entry
• Previous or current systems malignancy within the past 3 years
• Treatment with non approved or investigational drug within 2 weeks before study entry
• Any evidence of severe or uncontrolled systemic disease
• History of bleeding diathesis
• Any severe concomitant condition which makes it undesirable for the subject to participate in the study or which would jeopardize compliance with the study protocol