Breast Cancer Index (BCI) Registry

The BCI Registry is designed as a large-scale data registry and biospecimen repository to evaluate the clinical outcome of hormone receptor positive (HR+) early-stage breast cancer patients completing primary adjuvant endocrine therapy and are considering extended endocrine treatment. The impact of BCI test results on extended endocrine therapy decision-making and clinical use patterns will be characterized. Extended endocrine therapy-specific medication adherence will be assessed annually. Primary tumor tissue will be collected for scientific research purposes including molecular profiling and for correlative studies. The sample size will consist of approximately 3,000 subjects across 30-50 sites in the United States.

The BCI registry will recruit patients with HR+ stage I to III breast cancer following an initial 4-7 years of adjuvant endocrine therapy that will have BCI testing performed as part of routine clinical care and meet the inclusion/exclusion criteria. After signing the informed consent form (ICF) during screening, physicians and patients will complete the pre-test Decision Impact Questionnaire. Upon ordering BCI by the treating physician, primary tumor tissue obtained from the patient during previous breast-conserving surgery or mastectomy will be requested by Biotheranostics to perform BCI testing at Biotheranostics' CLIA certified and CAP accredited clinical laboratory in San Diego, CA. Following BCI testing, the physician will share and discuss the BCI results with their patients and recommend to either stop or extend endocrine therapy for an additional 5 years. The impact of the BCI test results on extended endocrine therapy decision-making will be assessed using the post-test Decision Impact Questionnaire, which will be completed by both physicians and patients. In addition, medication adherence will be evaluated in patients that are recommended for or elect to continue treatment to complete 10 years of adjuvant endocrine therapy.

BCI reports both a prognostic and predictive result and has been shown to significantly stratify patients based on the risk of late distant recurrence as well as to predict the likelihood of benefit from endocrine therapy in multiple prospective-retrospective studies within randomized controlled trial cohorts. The BCI registry study will determine the long-term outcome and BCI test performance to add prospective validation for the prognostic and predictive capabilities of BCI. In this context, the impact of BCI test results on treatment decision-making and subsequently prescribed treatments will be characterized.

Analysis of BCI test performance with long-term outcome will be performed by Kaplan-Meier analysis with log-rank test to assess the statistical significance of the risk stratification by BCI risk groups. Cox proportional hazards regression will be used to derive the hazard ratios (HR) and the associated 95% confidence intervals for the comparison of BCI risk groups. Univariate and multivariate analysis adjusting for clinical factors such as age, tumor size, grade, and treatment background (adjuvant endocrine therapy and chemotherapy) will be conducted. Descriptive statistics will be used to evaluate the decision-impact and medication adherence scores of patients enrolled in the study.