biostudies-literatureMamounas EPKorea Health Technology R&amp;D ProjectNCIBiotheranostics IncNCI NIH HHSBCRFNovartis, which provided letrozole and placebo to all study sites during the course of the study1984-1991https://www.ebi.ac.uk/biostudies/studies/S-EPMC11061597biostudies-literatureUnknown30(9)<h4>Purpose</h4>BCI (H/I) has been shown to predict extended endocrine therapy (EET) benefit. We examined BCI (H/I) for EET benefit prediction in NSABP B-42, which evaluated extended letrozole therapy (ELT) in patients with hormone receptor-positive breast cancer after 5 years of ET.<h4>Experimental design</h4>A stratified Cox model was used to analyze RFI as the primary endpoint, with DR, BCFI, and DFS as secondary endpoints. Because of a nonproportional effect of ELT on DR, time-dependent analyses were performed.<h4>Results</h4>The translational cohort included 2,178 patients (45% BCI (H/I)-High, 55% BCI (H/I)-Low). ELT showed an absolute 10-year RFI benefit of 1.6% (P = 0.10), resulting in an underpowered primary analysis (50% power). ELT benefit and BCI (H/I) did not show a significantClinical cancer research : an official journal of the American Association for Cancer ResearchBreast Cancer Index and Prediction of Extended Aromatase Inhibitor Therapy Benefit in Hormone Receptor-Positive Breast Cancer from the NRG Oncology/NSABP B-42 Trial.PMC11061597NCI U10CA 180868UG1 CA189867NCI U10CA 180822BCRF20-147BCRF 22-147)BCRF19-147U24 CA196067U10 CA180868U10 CA180822BCRF 21-147UG1CA189867Lucas PCBrufsky AMTreuner KFehrenbacher LWalshe JMPaik SSchnabel CABandos HZhang YChia SKMamounas EPSoori GSRastogi PGeyer CEDakhil SWolmark NSwain SMSgroi DCfalseBreast Cancer Index and Prediction of Extended Aromatase Inhibitor Therapy Benefit in Hormone Receptor-Positive Breast Cancer from the NRG Oncology/NSABP B-42 Trial.<h4>Purpose</h4>BCI (H/I) has been shown to predict extended endocrine therapy (EET) benefit. We examined BCI (H/I) for EET benefit prediction in NSABP B-42, which evaluated extended letrozole therapy (ELT) in patients with hormone receptor-positive breast cancer after 5 years of ET.<h4>Experimental design</h4>A stratified Cox model was used to analyze RFI as the primary endpoint, with DR, BCFI, and DFS as secondary endpoints. Because of a nonproportional effect of ELT on DR, time-dependent analyses were performed.<h4>Results</h4>The translational cohort included 2,178 patients (45% BCI (H/I)-High, 55% BCI (H/I)-Low). ELT showed an absolute 10-year RFI benefit of 1.6% (P = 0.10), resulting in an underpowered primary analysis (50% power). ELT benefit and BCI (H/I) did not show a significant2024-01-01T00:00:00Z2024 May2026-06-01T23:50:09.124Z2026-05-23T03:08:13.611ZS-EPMC110615973837691210.1158/1078-0432.CCR-23-1977