Gene Expression Following Short Term Exposure to Neoadjuvant Endocrine Therapy in Invasive Breast Cancer

Inclusion Criteria:

Postmenopausal patients, defined as one or more of the following criteria:

Documented history of bilateral oophorectomy, Aged 60 years or more,

Aged 45-59 years and satisfying one or more of the following criteria:

Amenorrhea for at least 12 months and intact uterus Amenorrhea for less than 12 months and follicle stimulating hormone (FSH) concentrations within postmenopausal range including: patients who have had a hysterectomy and patients who have received hormone replacement therapy in the past.

Clinically palpable or non-palpable T1c or greater, ER positive invasive breast cancer diagnosed by outside core biopsy.
Outside diagnosis of invasive breast cancer confirmed at MSKCC
Palpable or non-palpable breast mass > 1cm highly suspicious for invasive breast cancer based on mammographic, ultrasound and/or physical examination findings and amenable to diagnostic core biopsy.
Core biopsy diagnosis of ER positive invasive breast cancer performed at MSKCC
Breast conserving surgery or mastectomy scheduled at MSKCC.
Informed consent obtained.

Exclusion Criteria:

Co-morbid conditions which would preclude use of aromatase inhibitors such as: previous hypersensitivity, severe hepatic insufficiency (SGOT or SGPT three times the upper limit of normal), severe renal insufficiency (creatinine clearance <10ml/min).

Prior radiation therapy to chest wall / breast.

Neoadjuvant chemotherapy
Hormone replacement therapy, tamoxifen or raloxifene treatment within past 3 months
ER negative breast cancer
History of active malignancy within the previous 5 years (except for nonmelanoma skin cancer and breast cancer)