The purpose of this study is to study patients presenting with stage IV breast cancer. Stage IV means that the breast cancer has spread to another part of the body outside the breast. This study is important because in different parts of the country some patients are being offered surgical treatment for the breast tumor and some are not. The doctors do not know if surgery for the breast tumor is helpful in patients with stage IV breast cancer. The doctors will collect information about the patient and their treatment to learn more about how patients and doctors make treatment decisions. The doctor will also collect blood samples and tissue samples for laboratory studies to learn more about tumors that have spread to other parts of the body.

Inclusion Criteria:

• Age 18 years or older
• Known or suspected Stage IV breast cancer with intact primary tumor
• Known or suspected Stage IV breast cancer with intact primary tumor, having begun systemic therapy within the past 12 months
• Known or suspected Stage IV breast cancer within 3 months of local breast surgery
• Known or suspected Stage IV breast cancer within 3 months of local breast surgery, having begun systemic therapy within the past 12 months

Exclusion Criteria:

• Primary breast cancer diagnosis made by FNA only and no pre-treatment core biopsy planned for diagnostic or research purposes.
• Failure of MSKCC or participating site to confirm Stage IV breast cancer diagnosis by biopsy within 30 days of study enrollment

Potential research subjects will be identified by a member of the patient's treatment team, either at the time of consultation with the breast surgeon or breast medical oncologist. Patients will be accrued from each of the 15 participating sites.