Prospective Observational Study Evaluating Treatment Decision Impact of Prosigna® in Early Stage Breast Cancer Patients

Inclusion Criteria:

Surgically resected node-negative, estrogen receptor-positive, HER2-negative early-stage invasive breast cancer (T1-T2, N0, pN0 (i+), pN0 (mol+), M0)

Estrogen receptor status will be evaluated by Immunohistochemistry (IHC) and more than 1% of stained tumor cells will be considered positive.
HER2 status will be evaluated by IHC and/or by in-situ fluorescence hybridization (0 or 1+, or 2+ will be considered negative in the absence of in-situ fluorescence hybridization).

Postmenopausal females, which is defined as:

Natural Amenorrhea > 12 months, regardless of age
Bilateral oophorectomy, regardless of age (the oophorectomy must have been carried out at least 4 weeks before entering the study)
Radiological castration with amenorrhea > 3 months, regardless of age
Hysterectomy and postmenopausal blood levels of FSH/LH
Able to give informed consent
Eligible for treatment of breast cancer with adjuvant chemotherapy, as determined by the treating physician
ECOG performance status of 0 or 1

Exclusion Criteria:

Tumor specimen from core needle biopsy (CNB)
Tumor stage T3-T4
Non-invasive breast cancer (e.g., Paget's disease, DCIS)
Tumors with nodes that are not N0, pN0 (i+), or pN0 (mol+)
Tumors that are estrogen receptor (ER) negative or HER2-positive
Have metastatic disease
Have received another genomic test for prognosis of early breast cancer (i.e., Oncotype Dx, Mammaprint, or BCI)
Unable to give informed consent
Unable to complete patient reported outcome surveys

Have contraindications for adjuvant chemotherapy, as determined by the treating physician

o Age, performance status, significant comorbidities, etc.

ECOG performance status > 1