Comparing Letrozole Given Alone to Letrozole Given With Avastin in Post-Menopausal Women Breast Cancer

Inclusion Criteria: All patients must meet the following criteria to be eligible for study entry: * Pathologically confirmed invasive ductal carcinoma or invasive lobular carcinoma of the breast, T2-T3 / T4a-c / N0-2 / M0, with positive estrogen and/or progesterone receptors, and Her-2-neu negative. Patients with inflammatory breast cancer will not be included (T4d). Patients previously treated patients with no measurable disease or patients with metastatic disease will be excluded. * Give written informed consent prior to study specific screening procedures, with the understanding that the patient has the right to withdraw from the study at any time, without prejudice. * Patients must be postmenopausal, defined as one of the following: * Patients \> 50 years of age with no spontaneous menses for at least 12 months, * Bilateral oophorectomy * Be ambulatory (outpatient) and have an ECOG PS \<1. * Patients must have measurable disease by mammogram and/or breast ultrasound (in special cases a dedicated breast MRI may be clinically indicated). The target lesion must not have been previously irradiated. * No prior chemotherapy. * Patients must have adequate organ and marrow function as defined as follows: absolute neutrophil count \> 1,500/mm3, hemoglobin \> 8.0 g/dl, platelets \> 75,000/mm3, total bilirubin \< 2 mg/dl, serum creatinine \< 2 mg/dl, Transaminases (AST, ALT) may be up to 2 x institutional upper limit of normal. In addition \< 1 gr of protein in 24 hr urine collection and urine protein/creatinine ratio \< 1.0. * No life threatening parenchymal disease or rapidly progressing disease warranting cytotoxic chemotherapy. * Hypertension must be controlled (\<150/100 mmHg). * Ejection Fraction \> 50% by echocardiogram. (LVEF greater than 75% at baseline should be reviewed and/or the test repeated as it may be falsely elevated). * No history of thrombosis during the previous 12 months. Exclusion Criteria: * Current, recent (within 4 weeks of the first infusion of this study), or planned participation in an experimental drug study other than this sponsor-investigator Bevacizumab cancer study. * Uncontrolled high blood pressure (\>150/100 mmHg). * Unstable angina * New York Heart Association (NYHA) Grade III or greater congestive heart failure * History of myocardial infarction or unstable angina within 12 months * History of stroke or TIA within 12 months * Clinically significant peripheral vascular disease * History of a bleeding disorder * Presence of central nervous system or brain metastases * Major surgical procedure, open biopsy, or significant traumatic injury within 28 days prior to Day 0, anticipation of need for major surgical procedure during the course of the study * Minor surgical procedures (excluding fine needle aspirations or core biopsies) within 5 days prior to Day 0 * Pregnant (positive pregnancy test) or lactating * Urine protein: creatinine ratio greater than or equal to 1.0 at screening or patients demonstrating \> 1 gr of protein in 24 hr urine collection within 4 weeks prior to study entry will not participate in the trial. * History of abdominal fistula, gastrointestinal perforation, or intra-abdominal abscess within 6 months prior to Day 0 * Serious, non-healing wound, ulcer, or bone fracture * Unwilling or unable to comply with the protocol for the duration of the study. * Psychiatric illness/social situations that would limit compliance with study requirements. * History of another malignancy within the last five years except non-melanoma skin cancer and carcinoma in-situ of uterine cervix. * Patients with metastatic disease.