Genomic Test Changed Breast Cancer Treatment Plans
A study found that genomic testing shifted therapy recommendations for 42% of early-stage breast cancer patients.
Updated on Sept. 28, 2026 in Cancer
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The BCI Registry Study, which analyzed nearly 3,000 patients, revealed that using the Breast Cancer Index test altered physicians' decisions regarding extended endocrine therapy in 42% of cases. In two-thirds of these instances, the genomic insights led doctors to recommend against continuing treatment.
Why it matters
Standard clinical factors like tumor size and grade often fail to capture the full picture for patients, leading to uncertainty or premature cessation of therapy. Genomic testing helps clarify long-term recurrence risks, especially since approximately 50% of hormone receptor-positive breast cancer recurrences occur after five years.
The BCI test altered therapy paths for 42% of patients, with two-thirds of those changes moving away from extended treatment. Nearly 3,000 patients were involved in the study, where 83% reported side effects from endocrine therapy.
The players
Sarah Cannon Research Institute
This oncology research organization served as the primary site for the BCI Registry Study.
Hartford HealthCare
This healthcare system is affiliated with the lead study author of the research.
Breast Cancer Index
This is a genomic test recognized by NCCN and ASCO guidelines for determining treatment necessity.
The details
The Breast Cancer Index test is currently recognized by NCCN and ASCO guidelines as a tool for guiding treatment decisions. By providing a 10-year recurrence risk assessment, the test helps manage the reality that many patients struggle to continue endocrine therapy due to persistent side effects.
Timeline
July 2026: An updated test report option was launched to provide 10-year risk context.
September 28, 2026: The study findings were published in JAMA Network Open.
Health Landscape
This study reinforces the diagnostic utility of genomic testing within the framework already established by NCCN and ASCO clinical practice guidelines. It marks a shift toward precision medicine where individual tumor biology, rather than static clinical metrics, dictates the intensity of endocrine therapy.
Patients may now have a more personalized way to determine if continuing endocrine therapy is necessary based on their specific risk profile. This could help those struggling with side effects—which were reported by 83% of participants—avoid unnecessary treatment while ensuring high-risk cases remain protected.
The takeaway
Patients should discuss the Breast Cancer Index test with their oncologists to determine if it can help personalize their long-term therapy plan. Reducing treatment burden through genomic insights can significantly improve quality of life for those managing HR-positive breast cancer.
Further reading
For more information on current treatment standards, visit the Cancer section.
Source note: This article includes information reported by Curetoday.
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