biostudies-literatureUnknown8(11)O'Regan RM<h4>Importance</h4>The Breast Cancer Index (BCI) previously identified premenopausal patients with tumors in which the ratio of expression of HOXB13 relative to IL17BR (hereafter, BCI [H/I]-low tumors) as likely to derive greatest benefit from ovarian function suppression (OFS)-containing adjuvant therapy in the Suppression of Ovarian Function Trial (SOFT) trial.<h4>Objectives</h4>To assess BCI as a predictive biomarker of benefit from exemestane plus OFS vs tamoxifen plus OFS and to validate BCI as a prognostic biomarker for premenopausal patients.<h4>Design, setting, and participants</h4>This prognostic study used a prospective-retrospective translational design within the Tamoxifen and Exemestane (TEXT) and SOFT trials (enrolled November 2003 to April 2011). Blinded BCI testing in all aJAMA network opene2540931https://www.ebi.ac.uk/biostudies/studies/S-EPMC12584034biostudies-literatureAssessment of Adjuvant Endocrine Therapy With Ovarian Function Suppression by Breast Cancer Index.PMC12584034Viale GSalim MSiuliukina NGomez HLRen YFrancis PAWalley BAO'Regan RMTreuner KLang IFleming GFSchnabel CAChini CLoibl SMunzone EGeyer CEDell'Orto PBonnefoi HRPuglisi FNicoletti SVLKammler RTondini CColleoni MZhang YZaman KCiruelos EMGoetz MPLoi SMartino SStearns VPagani ORegan MMfalseAssessment of Adjuvant Endocrine Therapy With Ovarian Function Suppression by Breast Cancer Index.<h4>Importance</h4>The Breast Cancer Index (BCI) previously identified premenopausal patients with tumors in which the ratio of expression of HOXB13 relative to IL17BR (hereafter, BCI [H/I]-low tumors) as likely to derive greatest benefit from ovarian function suppression (OFS)-containing adjuvant therapy in the Suppression of Ovarian Function Trial (SOFT) trial.<h4>Objectives</h4>To assess BCI as a predictive biomarker of benefit from exemestane plus OFS vs tamoxifen plus OFS and to validate BCI as a prognostic biomarker for premenopausal patients.<h4>Design, setting, and participants</h4>This prognostic study used a prospective-retrospective translational design within the Tamoxifen and Exemestane (TEXT) and SOFT trials (enrolled November 2003 to April 2011). Blinded BCI testing in all a2025-01-01T00:00:00Z2025 Nov2026-06-05T11:49:27.182Z2026-05-16T03:13:31.228ZS-EPMC125840344118276610.1001/jamanetworkopen.2025.40931