The Effect of Aromatase Inhibitors on Cardiovascular Risk Factors in Women With Breast Cancer

Inclusion Criteria: * Ambulatory women (aged 60-75), with a new diagnosis of nonmetastatic, hormone-receptor positive breast cancer, having undergone lumpectomy. They will not need chemotherapy and will have been prescribed but not yet started anastrazole. All will need a course of radiation therapy as part of usual care. Participants are instructed not to change their physical activity or eating habits over the period of the study. Comparisons are: * Identical to the cases except they are hormone-receptor negative and don't need hormonal therapy. * Healthy controls. Exclusion Criteria: * Nicotine usage * Metastatic breast cancer * Need for chemotherapy * AI other than anastrazole * Usage of steroids (equivalent of equal then or more than 7.5 mg prednisone x 3 months) * Clinically significant abnormality of thyroid function * Treatment with gonadal hormone replacement therapy within last 3 years * Status post unilateral/bilateral surgical oophorectomy * Having experienced a medical event, which may confound study outcomes \[e.g. heart attack, stroke, cancer (metastatic or newly diagnosed within last 5 years, except for non-melanoma skin cancer and breast), lupus, rheumatoid arthritis, chronic inflammatory disease\] * Medication-dependent diabetes mellitus or hypercholesterolemia. * Gastric surgery * Weight loss medication (prescription or over the counter)