On May 26, 2026 Hologic, Inc. and its subsidiary, Biotheranostics, Inc., reported new data demonstrating how the Breast Cancer Index (BCI) Test results influence extended endocrine therapy decisions for patients with early-stage, hormone receptor-positive (HR+) breast cancer. According to the latest analysis, physician recommendations for extended endocrine therapy increased by more than 30% among patients identified by the BCI Test as likely to benefit, while recommendations decreased by nearly 40% for those identified as unlikely to benefit.
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The BCI Test is the established test for extended endocrine therapy decision-making, with exclusive guideline recognition from the National Comprehensive Cancer Network (NCCN) and the American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) for this purpose. Both classify the BCI Test as the only genomic assay shown to predict who is likely to benefit from extended endocrine therapy beyond five years.2,3
More information on these findings will be presented at the 2026 ASCO (Free ASCO Whitepaper) Annual Meeting on June 1. The data come from a new analysis of the ongoing BCI Registry Study, which evaluates how physicians incorporate prognostic and predictive BCI Test results into real-world treatment decisions.
"Understanding who is likely to benefit from extended endocrine therapy is critical to personalizing care," said Sami Diab, M.D., Medical Director, Oncology at Hologic. "Findings from the BCI Registry Study continue to highlight the real-world impact of the Breast Cancer Index Test in helping physicians make more informed treatment recommendations for their patients."
Detailed findings from the analysis include:
Overall:
The percentage of patients recommended for extended endocrine therapy decreased from 54.6% before BCI testing to 41.2% after BCI testing.
The percentage of patients not recommended for extended endocrine therapy increased from 44.9% before testing to 58% after testing.
Among patients identified by the BCI Test as likely to benefit from extended endocrine therapy (BCI H/I-High):
Physician recommendations for extended endocrine therapy increased from 60.4% before testing to 90.6% after testing.
Among patients identified as unlikely to benefit (BCI H/I-Low):
Recommendations decreased from 51.1% to 11.8%.
"Decisions about extended endocrine therapy are complex, requiring physicians to balance recurrence risk, potential side effects, and clinical and pathologic factors," said Tara B. Sanft, M.D., of Hartford Healthcare and lead author of the study. "Findings from the BCI Registry Study suggest that relying on those factors alone may not provide enough information for physicians and patients to make decisions with confidence. Genomic testing with the Breast Cancer Index Test provides additional insight into tumor biology, helping physicians refine extended endocrine therapy recommendations and better identify which patients are most likely to benefit."
Learn more on June 1, 2026, 1:30-4:30 p.m. CDT at ASCO (Free ASCO Whitepaper) 2026: Impact of the Breast Cancer Index on Extended Endocrine Therapy Recommendations in Patients from the BCI Registry Study1 (Abstract #527/Poster Board #12 — Breast Cancer — Local/Regional/Adjuvant)
About the Breast Cancer Index Test
The Breast Cancer Index Test is a molecular, gene expression-based test uniquely positioned to provide information to help physicians individualize treatment decisions for patients with early-stage, HR+ breast cancer. This breakthrough test helps oncology care teams and patients navigate the difficult trade-offs between taking steps to prevent recurrence of their disease and facing significant side effects and safety challenges related to unnecessary treatment.
The Breast Cancer Index Test has guideline designation from the American Joint Committee on Cancer for cancer staging based on molecular profile. The ASCO (Free ASCO Whitepaper) Clinical Practice Guideline and the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) acknowledge the Breast Cancer Index Test as a biomarker to help inform extended endocrine treatment decisions.2,3
The Breast Cancer Index Test is intended for routine clinical use, and physician treatment decisions based on results are the responsibility of the physician. It is a sole-source laboratory-developed test (LDT) performed by Biotheranostics, Inc., a CLIA-certified and CAP-accredited diagnostic laboratory. It has not been cleared or approved by the U.S. Food and Drug Administration. For more information, visit www.breastcancerindex.com.
(Press release, Hologic, MAY 26, 2026, View Source [SID1234666072])