The EMPOwER Study Evaluating Multiparameter Gene Testing as a Predictor of Short Term Endocrine Therapy Response in Hormone Receptor Positive Breast Cancers

Evaluating Multiparameter Gene Testing as a Predictor of Short Term Endocrine Therapy Response in Hormone Receptor Positive Breast Cancers: The EMPOwER Study

Evaluating Multiparameter Gene Testing as a Predictor of Short Term Endocrine Therapy Response in Hormone Receptor Positive Breast Cancers

The clinical trial will be a prospective, two strata, non-blinded, single institution, Health Canada approved, Window of Opportunity trial with 2 weeks of pre-surgical endocrine therapy using either anastrozole or tamoxifen. Tissue from the initial biopsy and from surgery will be sent for Ki67 analysis using the NanoString® Assay.

Inclusion Criteria:

• Any patient with histologically confirmed newly diagnosed operable ER+, Her2 negative invasive carcinoma on diagnostic core biopsy that has a radiographic size ≥ 1.5 cm
• Histology has to be ductal, lobular or mixed
• Surgery date planned in the next 2-6 weeks
• Negative pregnancy test if of child baring potential
• Post-menopausal status verified by FSH and Estradiol (with 6 months of amenorrhea)

Exclusion Criteria:

• Previous treatment with endocrine therapy, chemotherapy or chest wall radiation within last 6 months
• Known metastatic or recurrent breast cancer.