Multicenter cohort study of impact of Breast Cancer Index on recommendations for extended endocrine therapy

The Breast Cancer Index (BCI) is an established genomic assay that provides individualized risks of overall and late distant recurrence and predicts the likelihood of extended endocrine therapy (ET) benefit in patients with early stage, HR-positive breast cancer. The multicenter BCI Registry study in the USA evaluated the clinical impact of the BCI on physicians’ decisions and confidence in extending ET and on patients’ preference and comfort with the decision. In this cohort study of 2900 women, completed physician and patient questionnaires were analyzed. After BCI testing, 41.7% of physicians changed their extended ET recommendation, with a 43.8% increase in their confidence, and 51.0% of patients changed their preference for extended ET. The authors conclude that these findings demonstrate that BCI provides clinical utility in guiding extended ET.