A prospective decision-impact study incorporating Breast Cancer Index into extended endocrine therapy decision-making

To prospectively assess the impact of gene expression-based assay Breast Cancer Index (BCI) on extended endocrine therapy (EET) decision-making. The BCI-tested samples from primary tumors (Stage I-III, hormone receptor positive breast cancer, >3.5 year endocrine therapy). Patients and physicians completed questionnaires on EET preferences and decision conflict. Using these data, a fact-based economic model was developed to project the cost impact of BCI. The BCI results affected treatment recommendations for 42/141 patients (overall mean, 62 year; 83% postmenopausal; 63% Stage I). Patient decision conflict decreased pre- to post-test. The BCI-related projected net savings (US$5190/patient) was robust under sensitivity analysis. Incorporating BCI into clinical practice meaningfully impacted physician EET recommendations and decreased patient decision conflict, with projected cost savings.