Endocrine Therapy in Treating Patients With HER2 Negative, Low Risk Breast Cancer

PRIMARY OBJECTIVES: I. To estimate the conversion rate from a standard low-toxicity approach to guideline-directed therapy which includes surgery +/- radiation therapy as a result of progression of disease or patient/provider choice. II. To examine factors that might differ between those who convert from the low-toxicity approach to the guideline-directed therapy and those do not convert. SECONDARY OBJECTIVES: I. To measure the safety and clinical effectiveness of systemic endocrine therapy used in a prolonged neoadjuvant fashion. II. To evaluate the impact of risk-stratified care in Quality-Adjusted Life Years (QALY) and QALY gains. III. To estimate the cost savings of indefinitely delaying surgery and radiation in favor of systemic endocrine therapy alone. OUTLINE: Patients receive exemestane orally (PO) once daily (QD), anastrozole PO QD, letrozole PO QD, tamoxifen citrate PO QD, or toremifene citrate PO QD at the discretion of the treating physician. Treatment continues in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed up periodically.