Randomized Phase II Study of Preoperative Letrozole (Femara) in Combination With Avastin in Hormone Receptor Positive Breast Cancer

Inclusion Criteria: * Histologically confirmed operable or potentially operable invasive breast adenocarcinoma that is clinically palpable and measurable * Age ≥ 18 years * Clinical Stage T2-4, N0-3, M0 (Stage II-III) * Postmenopausal defined as Age ≥ 60 years and/or Age \>45 years with amenorrhea 12 months with an intact uterus and/or History of bilateral oophorectomy and/or FSH and estradiol levels in postmenopausal range * ECOG PS 0, 1 * Unifocal disease * ER and/or PR positive * Adequate hematological, renal, and hepatic functions Absolute neutrophil count ≥ 1,500/µL Platelet count ≥ 100,000/µL creatinine ≤ 1.5 mg/dL Serum total bilirubin ≤ 1.5 mg/dL Alkaline phosphatase ≤ 3X the ULN for the reference lab SGOT/SGPT ≤ 3X the ULN for the reference lab * Patients or their legal representatives must be able to read, understand and provide informed consent to participate in the trial * Use of effective means of contraception (men and women) in subjects of child-bearing potential Exclusion Criteria: * Prior history of and/or therapy for invasive breast cancer (includes chemotherapy, radiation, hormonal therapy including AIs, tamoxifen, raloxifene, fulvestrant or any other antiestrogen/SERM) * Clinically significant cardiovascular disease, EF \<50% * Known CNS disease * History of deep vein thrombosis or pulmonary embolism * Proteinuria at screening as demonstrated by either Urine protein:creatinine (UPC) ratio ≥ 1.0 at screening OR Urine dipstick for proteinuria ≥ 2+ (patients discovered to have ≥2+ proteinuria on dipstick urinalysis at baseline should undergo a 24 hour urine collection and must demonstrate ≤ 1g of protein in 24 hours to be eligible). * Presence of non-healing wound or fracture * Current, recent (within 4 weeks of the first infusion of this study), or planned participation in an experimental drug study other than a Genentech-sponsored bevacizumab cancer study * Inadequately controlled hypertension (defined as systolic blood pressure \>150 and/or diastolic blood pressure \> 100 mmHg on antihypertensive medications) * Any prior history of hypertensive crisis or hypertensive encephalopathy * New York Heart Association (NYHA) Grade II or greater congestive heart failure (see Appendix E) * History of myocardial infarction or unstable angina within 12 months prior to study enrollment * Any history of stroke or transient ischemic attack at any time * Significant vascular disease (e.g., aortic aneurysm, aortic dissection) * Symptomatic peripheral vascular disease * Evidence of bleeding diathesis or coagulopathy * Major surgical procedure, open biopsy, or significant traumatic injury within 28 days prior to Day 0 * Core biopsy or other minor surgical procedures such as fine needle aspirations or core biopsies within 7 days prior to Day 0 * Pregnant (positive pregnancy test) or lactating. Use of effective means of contraception (men and women) in subjects of child-bearing potential is mandatory * History of abdominal fistula, gastrointestinal perforation, or intra-abdominal abscess within 6 months prior to Day 0 * Known hypersensitivity to any component of bevacizumab or letrozole * Inability to comply with study and/or follow-up procedures