Hologic Showcases New ASCO 2026 Data Highlighting the Role of the Breast Cancer Index® Test in Guiding Extended Endocrine Therapy Decisions
Hologic and its subsidiary Biotheranostics have announced new clinical data showing how the Breast Cancer Index® (BCI™) Test is influencing physician decision-making regarding extended endocrine therapy in patients with early-stage hormone receptor-positive breast cancer. The findings, which will be presented at the ASCO Annual Meeting 2026, further support the growing role of genomic testing in personalizing long-term breast cancer treatment strategies.
According to the latest analysis from the ongoing BCI Registry Study, physician recommendations for extended endocrine therapy increased significantly among patients identified by the Breast Cancer Index Test as likely to benefit from continued treatment beyond five years. At the same time, recommendations declined substantially among patients classified as unlikely to benefit, suggesting that genomic testing may help clinicians make more tailored treatment decisions while potentially reducing unnecessary therapy exposure.
The Breast Cancer Index Test is currently recognized by both the National Comprehensive Cancer Network and the American Society of Clinical Oncology as the only genomic assay specifically shown to predict which patients are likely to benefit from extended endocrine therapy after the standard initial five-year treatment period. This exclusive guideline recognition has positioned the assay as an important decision-support tool in the management of hormone receptor-positive breast cancer.
Hormone receptor-positive breast cancer is one of the most common forms of breast cancer and is typically treated with endocrine therapy designed to block or suppress hormone signaling that drives tumor growth. Standard endocrine therapy is commonly administered for five years following surgery and other initial treatments. However, determining whether patients should continue endocrine therapy beyond that timeframe remains a complex clinical question.
Extended endocrine therapy can reduce the risk of recurrence for some patients, but prolonged treatment may also lead to side effects including bone loss, joint pain, fatigue, cardiovascular risks, menopausal symptoms, and reduced quality of life. As a result, oncologists must carefully balance the potential benefits of continued therapy against the physical and emotional burden associated with long-term treatment.
The newly reported data suggest that genomic testing with the Breast Cancer Index may help refine those decisions by providing additional insight into tumor biology and recurrence risk that cannot be fully captured through traditional clinical and pathological factors alone.
The findings originate from the ongoing BCI Registry Study, a real-world observational study designed to evaluate how physicians incorporate prognostic and predictive Breast Cancer Index results into treatment planning for patients with early-stage hormone receptor-positive breast cancer.
One of the key observations from the latest analysis involved the overall impact of BCI testing on physician recommendations. Before receiving Breast Cancer Index results, approximately 54.6% of patients were recommended for extended endocrine therapy. After physicians reviewed the BCI results, that percentage declined to 41.2%.
Conversely, the percentage of patients not recommended for extended endocrine therapy increased from 44.9% before testing to 58% after testing. These findings suggest that the genomic assay may help physicians avoid unnecessary continuation of therapy in patients unlikely to derive meaningful benefit.
The study also demonstrated particularly strong shifts in treatment recommendations when patients were stratified according to their Breast Cancer Index predictive category.
Among patients identified by the test as likely to benefit from extended endocrine therapy, categorized as BCI H/I-High, physician recommendations for continuing therapy increased dramatically following test results. Before BCI testing, 60.4% of these patients were recommended for extended endocrine therapy. After physicians reviewed the genomic data, recommendations increased to 90.6%.
In contrast, among patients categorized as BCI H/I-Low and identified as unlikely to benefit from extended therapy, physician recommendations decreased sharply. Prior to testing, 51.1% of these patients were advised to continue endocrine therapy. Following receipt of BCI results, that number fell to just 11.8%.
These changes indicate that the test may significantly influence physician confidence in tailoring long-term treatment strategies according to the biological characteristics of individual tumors.
Dr. Sami Diab, Medical Director of Oncology at Hologic, said the findings underscore the importance of identifying which patients are most likely to benefit from extended endocrine therapy. According to Diab, personalized treatment decisions are becoming increasingly important as oncology moves toward more individualized approaches based on tumor biology and patient-specific risk profiles.
He noted that results from the BCI Registry Study continue to demonstrate the practical impact of the Breast Cancer Index Test in helping physicians make more informed treatment recommendations in real-world clinical settings.
The growing use of genomic assays in breast cancer reflects broader trends in precision oncology, where molecular profiling tools are increasingly used to guide treatment intensity, recurrence risk assessment, and therapy duration decisions.
Traditional decision-making for extended endocrine therapy has historically relied on a combination of clinical and pathological features such as tumor size, lymph node involvement, tumor grade, patient age, and recurrence risk estimates. While these factors remain important, they may not fully capture the underlying biological behavior of individual tumors.
Dr. Tara B. Sanft of Hartford HealthCare, lead author of the study, stated that decisions surrounding extended endocrine therapy remain highly complex because physicians must weigh recurrence risk alongside treatment side effects and patient quality-of-life considerations.
According to Sanft, the findings suggest that relying solely on conventional clinical and pathological factors may not provide enough information for patients and physicians to make decisions with optimal confidence. She explained that genomic testing with the Breast Cancer Index provides additional biological insight that can help refine treatment recommendations and better identify patients most likely to benefit from ongoing therapy.
This personalized approach may become increasingly important as survivorship care evolves and more patients live for many years after early-stage breast cancer treatment. Avoiding overtreatment while maintaining strong protection against recurrence has become a major goal within modern oncology practice.
The Breast Cancer Index Test has gained attention because of its dual prognostic and predictive capabilities. In addition to estimating the risk of late distant recurrence, the assay is designed to predict whether a patient is likely to derive benefit from continuing endocrine therapy beyond five years.
This predictive capability differentiates the test from many other genomic assays used in breast cancer management, which may focus primarily on recurrence risk without directly informing decisions regarding extended endocrine treatment duration.
As clinical practice continues shifting toward more individualized care strategies, tools capable of helping physicians tailor therapy duration may become increasingly valuable for optimizing both outcomes and patient quality of life.
The real-world nature of the BCI Registry Study is also notable because it evaluates how genomic information influences physician behavior outside of highly controlled clinical trial settings. Real-world evidence has become an increasingly important component of oncology research because it reflects how diagnostic technologies and treatments are used across broader patient populations in routine practice.
The new findings will be formally presented during a poster session at the ASCO 2026 Annual Meeting on June 1, 2026. The presentation, titled “Impact of the Breast Cancer Index on Extended Endocrine Therapy Recommendations in Patients from the BCI Registry Study,” will be featured in the Breast Cancer — Local/Regional/Adjuvant category as Abstract #527 and Poster Board #12.
The ASCO Annual Meeting remains one of the largest and most influential global oncology conferences, serving as a major venue for presenting advances in cancer diagnostics, therapeutics, precision medicine, and survivorship care.
The continued expansion of genomic testing in breast cancer management reflects broader efforts across oncology to align treatment decisions more closely with the biological characteristics of individual tumors. By helping physicians distinguish patients who are likely to benefit from prolonged endocrine therapy from those who may safely avoid additional years of treatment, the Breast Cancer Index Test may support more personalized and evidence-based long-term care planning.
For patients, these types of tools may help reduce uncertainty surrounding extended therapy decisions while potentially minimizing exposure to unnecessary side effects. For clinicians, genomic assays capable of providing predictive treatment information may improve confidence in balancing recurrence prevention with quality-of-life considerations.
As the field of precision oncology continues to evolve, studies such as the BCI Registry analysis highlight the growing role of molecular diagnostics in shaping individualized cancer treatment strategies and supporting more nuanced clinical decision-making in survivorship care.
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® 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.
About Hologic, Inc.
Hologic, Inc. is a global leader in women’s health dedicated to developing innovative medical technologies that effectively detect, diagnose and treat health conditions and raise the standard of care around the world.
