Breast Cancer Index (BCI) is an RT-PCR assay performed on FFPE breast tumor tissue that integrates two gene expression-based biomarkers: 1) the HOXB13:IL17BR ratio (H/I), which is associated with tumor responsiveness to endocrine therapy; and 2) Molecular Grade Index (MGI), which consists of the average expression of five cell cycle-associated genes (BUB1B, CENPA, NEK2, RACGAP1 and RRM2) and provides quantitative and objective molecular assessment of tumor proliferative status. The Breast Cancer Index (BCI) Risk of Recurrence & Extended Endocrine Benefit Test is indicated for use in women diagnosed with hormone receptor-positive (HR+), lymph node-negative (LN-) or lymph node positive (LN+; with 1-3 positive nodes) early-stage, invasive breast cancer, who are distant recurrence-free. The BCI test provides: 1) a quantitative estimate of the risk for both late (post-5 years from diagnosis) distant recurrence and of the cumulative distant recurrence risk over 10 years (0-10y) in patients treated with adjuvant endocrine therapy (LN- patients) or adjuvant chemoendocrine therapy (LN+ patients), and 2) prediction of the likelihood of benefit from extended (>5 year) endocrine therapy.