Bevacizumab Given With Either Anastrozole or Fulvestrant With Trastuzumab for Postmenopausal Metastatic Breast Cancer

Regimen A: Bevacizumab/anastrozole (with trastuzumab in HER2+ patients). Bevacizumab 10mg/kg IV every 2 weeks \[patients who are also receiving trastuzumab have the option to receive their bevacizumab at 15 mg/kg every 3 weeks instead of 10 mg/kg every 2 weeks (see Trastuzumab section below)\] and anastrozole (1 mg orally daily). Treatment will be given in 4-week cycles. Response assessments will be performed after 2 cycles. Patients who respond to treatment or have stable disease will continue to be evaluated every 2 cycles. After 6 months, response assessment will occur every 3 months. A patient may remain on study if radiation is deemed necessary and appropriate, provided that there are other sites of measurable disease outside the field of radiation that may be followed. Treatment occurs until disease progression. Patients will be selected for this treatment arm per the following guidelines: \>=12 months from adjuvant endocrine therapy OR \>=12 months from adjuvant aromatase inhibitors OR Endocrine therapy naive OR Prior tamoxifen exposure or tamoxifen intolerance Regimen B: Bevacizumab/fulvestrant (with trastuzumab in HER2+ patients). Bevacizumab 10mg/kg IV every 2 weeks \[patients who are also receiving trastuzumab have the option to receive their bevacizumab at 15 mg/kg every 3 weeks instead of 10 mg/kg every 2 weeks (see Trastuzumab section below)\] fulvestrant (500 mg intramuscular on Day 1 of Cycle 1, followed by 250 mg intramuscular of fulvestrant on Day 15 of Cycle 1. On Day 1 of Cycle 2 and the first day of all subsequent cycles thereafter, patients in this treatment arm will receive 250 mg intramuscularly of fulvestrant). Treatment will be given in 4-week cycles. Response assessments will be performed after 2 cycles. Patients who respond to treatment or have stable disease will continue to be evaluated every 2 cycles. After 6 months, response assessment will occur every 3 months. A patient may remain on study if radiation is deemed necessary and appropriate, provided that there are other sites of measurable disease outside the field of radiation that may be followed. Treatment occurs until disease progression. Patients will be selected for this treatment arm per the following guidelines: \<12 months from adjuvant aromatase inhibitor therapy OR Intolerant of aromatase inhibitors OR Disease progression on adjuvant aromatase inhibitors OR Physician discretion Trastuzumab: Patients in Treatment Arm A or Treatment Arm B who have FISH HER2+ or IHC3+ breast cancer will also receive treatment with trastuzumab in addition to their treatment with the combination of bevacizumab with either anastrozole or fulvestrant. Trastuzumab will be administered ONLY to patients with HER2+ breast cancer (FISH-positive or IHC3+). An 8 mg/kg loading dose of IV trastuzumab will be administered on Day 1, followed by doses of 6 mg/kg IV trastuzumab once every 3 weeks. These patients will have the option of receiving their bevacizumab doses at 15 mg/kg every 3 weeks rather than 10 mg/kg every 2 weeks (if they prefer to keep their bevacizumab dosing schedule consistent with their trastuzumab dosing schedule so that the number of visits they must make to the study site is minimized). The dosing schedules for anastrozole (for HER2+ patients in Treatment Arm A) and fulvestrant (for HER2+ patients in Treatment Arm B) will not change.