Molecular Analyses to Predict Pathways of Endocrine Resistance Following Short Term Neoadjuvant Endocrine Treatment in Patients With Hormone Receptor-Positive HER2-negative Breast Cancer

Inclusion Criteria

• •1. Unilateral diagnostic breast mammogram and ultrasound within 60 days of enrollment.
• •2. Pathologically proven diagnosis of invasive breast cancer, clinical stage I or II.
• •3. Patients must be clinically lymph node negative. Lymph node negativity must be confirmed by clinical exam and/or ultrasound imaging.
• •4. The patient must be female.
• •5. Age ≥18 years.
• •6. Estrogen and/or progesterone receptor positive tumor defined ≥1% positively staining cells by immunohistochemistry, according to the current American Society of Clinical Oncology/College of American Pathologists guidelines.
• •7. Human epidermal growth factor receptor 2 (HER2) /neu must be negative by immunohistochemistry (IHC) or fluorescence in situ hybridization (FISH).
• •8. Eastern Cooperative Oncology Group (ECOG) performance status 0 to 2.
• •9. Bilateral breast cancer and/or multifocal, multicentric disease is allowed.
• •10. Appropriate pretreatment evaluations for protocol entry, including no clinical evidence for distant metastases, based upon the following minimum diagnostic workup: history/physical examination, including breast exam (inspection and palpation of the breasts), clinically negative axillary lymph nodes, within 28 days prior to study entry.
• •11. The patient must qualify for endocrine treatment (treatment of choice), per the treating medical oncologist.
• •12. The patient must provide study-specific informed consent prior to study entry.
• •13. Patients with a prior history of breast cancer will be considered eligible, if they have completed all treatment (including endocrine therapy) more than two years prior to registration.
• •14. Patients must not have had a prior treatment for this breast cancer or for any malignancy diagnosed or treated within the past two years, with the exception of non-melanomatous skin cancer, carcinoma in situ of the cervix.
• •15. Women of childbearing age will be advised to use adequate methods of contraception. Adequate methods of contraception for premenopausal women include barrier methods and/or non-hormonal methods (Intrauterine devices etc.).
• •16. Strong cytochrome P450 2D6 (CYP2D6) inhibitors will be prohibited with tamoxifen, as it can decrease the efficacy of tamoxifen. There are no known strong interactions with aromatase inhibitors.