A Prospective Observational Study of Clinical Outcomes for the NanoString® Technologies Prosigna™ Gene Signature Assay

Inclusion Criteria:

• 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 (0 or 1+, or 2+ will be considered negative) and by in-situ fluorescence hybridization.

• Postmenopausal women 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
• Able to give consent
• Eligible for treatment of breast cancer with adjuvant chemotherapy
• ECOG performance status of 0 or 1

Exclusion Criteria:

• Tumor size 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 negative or HER2 positive
• Have metastatic disease
• Unable to give informed consent
• Unable to complete patient reported outcome surveys

• Have contraindications for adjuvant chemotherapy

  • Age, performance status, significant comorbidities
• ECOG performance status > 1