Breast Cancer Index

**Semantic type:** Laboratory Procedure

**Definition:** A proprietary gene expression-based test that analyzes the activity of seven genes to predict the benefits from extended endocrine therapy in early-stage, lymph node-negative, hormone receptor-positive breast cancer. The Breast Cancer Index reports two results: how likely the cancer is to come back 5 to 10 years after initial diagnosis and if a patient is likely to benefit from taking hormonal therapy for an additional 5 years (total of 10 years).

**Synonyms:** - BCI