This is a prospective study that will assess the impact of MammaPrint on chemotherapy + endocrine versus endocrine alone treatment decisions in patients with an Oncotype Intermediate Score.

The frequency of chemotherapy + endocrine versus endocrine alone decisions in Oncotype DX intermediate score patients will be calculated before and after receiving the MammaPrint result.

Inclusion Criteria:

• Women with histologically proven invasive stage I-II, node negative, hormone receptor positive, Her2 negative breast cancer, who received an Oncotype DX intermediate score (18-30)
• ≥ 18 years of age at time of consent
• Written informed consent

Exclusion Criteria:

• Insufficient tissue remaining for Mammaprint FFPE
• Tumor sample shipped to Agendia with ≤ 30% tumor cells or that fails QA or QC criteria
• Women who have started or completed adjuvant chemotherapy or neo-adjuvant chemotherapy

Patients with an Intermediate Recurrence Score