biostudies-literatureUnknown30(9)Blasco AGEICAM Spanish Breast Cancer Group<h4>Importance and objective</h4>Several definitions of efficacy endpoints have been proposed for clinical trials in early breast cancer (EBC). Invasive disease-free survival (IDFS) and other endpoints have been used as surrogates for overall survival (OS) in adjuvant trials. The aim was to evaluate these endpoints in a comparative way in a large cohort of patients to assess whether they are appropriate surrogates for OS.<h4>Participants and design</h4>Individual patient data from 8 phase III randomized adjuvant chemotherapy (CT) trials for EBC were analyzed. Trial-level surrogacy analyses were conducted using weighted least squares regression to assess the association between treatment effects on surrogates at different time points-IDFS and other defined endpoints (by STEEP v2.0)-and OS. The oncologistoyaf263https://www.ebi.ac.uk/biostudies/studies/S-EPMC12450318biostudies-literatureIntermediate endpoints as surrogates for long-term outcomes in breast cancer adjuvant chemotherapy trials.PMC12450318Lopez-Tarruella SCalvo LChan AUrruticoechea AGarcia-Saenz JABermejo BPienkowski TRuiz-Borrego MSlamon DHerranz JSpera GGuerrero-Zotano AMartin MChap LCrown JSemiglazov VCarrasco EBlasco AfalseIntermediate endpoints as surrogates for long-term outcomes in breast cancer adjuvant chemotherapy trials.<h4>Importance and objective</h4>Several definitions of efficacy endpoints have been proposed for clinical trials in early breast cancer (EBC). Invasive disease-free survival (IDFS) and other endpoints have been used as surrogates for overall survival (OS) in adjuvant trials. The aim was to evaluate these endpoints in a comparative way in a large cohort of patients to assess whether they are appropriate surrogates for OS.<h4>Participants and design</h4>Individual patient data from 8 phase III randomized adjuvant chemotherapy (CT) trials for EBC were analyzed. Trial-level surrogacy analyses were conducted using weighted least squares regression to assess the association between treatment effects on surrogates at different time points-IDFS and other defined endpoints (by STEEP v2.0)-and OS. 2025-01-01T00:00:00Z2025 Sep2026-06-29T03:22:36.2Z2026-06-29T03:19:47.522ZS-EPMC124503184083887210.1093/oncolo/oyaf263