Alternative Dosing of Exemestane before Surgery in Treating Postmenopausal Patients with Stage 0-II Estrogen Positive Breast Cancer

Inclusion Criteria

• Postmenopausal women (postmenopausal: age >= 60 years, or amenorrhea >= 12 months, or bilateral oophorectomy, or - in women with hysterectomy only - follicle stimulating hormone [FSH] in the menopausal levels as per local institutional guidelines if < 60 years old) with histologically-confirmed estrogen receptor (ER)-positive (>= 10%) primary breast cancer stage cT0-2, cN0-1, Mx; women with larger tumors who refuse chemotherapy (chemo) and/or endocrine neoadjuvant therapy can be eligible
• Eastern Cooperative Oncology Group (ECOG) performance status =< 1 (Karnofsky >= 70%)
• Leukocytes >= 3,000/microliter
• Absolute neutrophil count >= 1,500/microliter
• Platelets >= 100,000/microliter
• Total bilirubin =< 2 x institutional upper limit of normal (ULN)
• Aspartate aminotransferase (AST) (serum glutamic oxaloacetic transaminase [SGOT])/alanine aminotransferase (ALT) (serum glutamate pyruvate transaminase [SGPT]) =< 1.5 x institutional ULN
• Serum creatinine =< 1.5 times institutional ULN
• Ability to understand and the willingness to sign a written informed consent document

Exclusion Criteria

• Body mass index (BMI) < 18.5 Kg/m^2
• Previous treatment for breast cancer including chemotherapy, endocrine therapy and radiotherapy; women with prior ductal breast carcinoma in situ (DCIS) who were treated with surgery only and whose treatment ended >= 2 years prior to enrollment are eligible for the trial
• Women who are planned to receive neoadjuvant therapy
• Participants may not be receiving investigational agents
• History of allergic reactions attributed to compounds of similar chemical or biologic composition to exemestane
• Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements
• Other co-existing invasive malignancies (with the exclusion of basal cell carcinoma or skin squamous cell carcinoma) diagnosed during the last 2 years before randomization
• History of severe osteoporosis (T score =< -4 either spine or hip), or presence of vertebral fracture
• Use of systemic hormone replacement therapy (HRT) in the last 30 days prior to the randomization; the use of non-systemic estrogen (such as vaginal estrogen use) is allowed
• Use of any chemopreventive agents (selective estrogen receptor modulators [SERM]) in the last 3 months
• Concomitant use of CYP3A4 inducer medication (rifampicin, phenytoin, carbamazepine, phenobarbital, and St. John’s wort)