{"entity":{"id":"breast-cancer-index","kind":"drug","name":"Breast Cancer Index","aka":[],"tldr":"The only test designed to tell a woman who has finished five years of hormone therapy whether another five years is worth the side effects.","summary":"Breast Cancer Index (Biotheranostics, acquired by Hologic in 2021) is a laboratory-developed test for hormone-receptor-positive early breast cancer. Its HOXB13:IL17BR component was shown to predict benefit from extending endocrine therapy to 10 years in the MA.17, Trans-aTTom and IDEAL trial cohorts, and the ASCO and NCCN guidelines list it as the test for that decision; a prespecified NSABP B-42 analysis was less clear-cut. It also gives a late-recurrence risk (years 5 to 10). Medicare covers it. The test does not address the initial chemotherapy decision, which is the province of Oncotype DX, MammaPrint, Prosigna and EndoPredict.","status":"established","asOf":"2026-09-10","links":[{"label":"Breast Cancer Index","url":"https://www.breastcancerindex.com"},{"label":"ASCO biomarker guideline update (2022)","url":"https://doi.org/10.1200/JCO.22.00069"}],"tags":["test"],"related":["oncotype-dx","endopredict"],"cancers":["breast-hr-positive"],"sections":[],"technologies":["rna-seq","endocrine-therapy"],"targets":[],"drugs":[],"companies":["hologic"],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":["paper-andre-j-clin-oncol"],"journals":[],"dependsOn":[],"notes":["What a result means: 'BCI (H/I) high' predicts that continuing hormone therapy past five years reduces recurrence; 'low' means the extra years add side effects without measurable benefit."],"brand":"Breast Cancer Index (BCI)","modality":"Gene-expression prognostic and predictive assay (extended endocrine therapy benefit)","mechanism":"RT-PCR combining the HOXB13:IL17BR ratio (predicts benefit from extended endocrine therapy) with the Molecular Grade Index (prognosis for late recurrence).","approvals":[],"mechanismSteps":[],"toxicity":[],"access":[],"regulatoryEvents":[]},"route":"/drugs/breast-cancer-index/","neighbours":{"drug":[{"id":"endopredict","kind":"drug","name":"EndoPredict","route":"/drugs/endopredict/"},{"id":"oncotype-dx","kind":"drug","name":"Oncotype DX","route":"/drugs/oncotype-dx/"}],"cancer":[{"id":"breast-hr-positive","kind":"cancer","name":"HR-positive / HER2-negative breast cancer","route":"/cancers/breast-hr-positive/"}],"technology":[{"id":"endocrine-therapy","kind":"technology","name":"Endocrine therapy (SERMs, AIs, SERDs)","route":"/technologies/endocrine-therapy/"},{"id":"rna-seq","kind":"technology","name":"RNA sequencing & expression profiling","route":"/technologies/rna-seq/"}],"company":[{"id":"hologic","kind":"company","name":"Hologic","route":"/companies/hologic/"}],"paper":[{"id":"paper-andre-j-clin-oncol","kind":"paper","name":"Biomarkers for Adjuvant Endocrine and Chemotherapy in Early-Stage Breast Cancer: ASCO Guideline Update","route":"/key-papers/paper-andre-j-clin-oncol/"}],"roadmap":[{"id":"hormonal-therapy-roadmap","kind":"roadmap","name":"Hormonal therapy roadmap: removing the ovaries → tamoxifen → oral degraders switched by a blood test","route":"/roadmaps/hormonal-therapy-roadmap/"}],"target":[{"id":"hoxb13","kind":"target","name":"HOXB13","route":"/targets/hoxb13/"}]}}