Sensitivity to Endocrine Therapy Index Predicts Benefit from Weekly Adjuvant Paclitaxel for Hormone Receptor–Positive Breast Cancer in the GEICAM/9906 Trial

Clinical Cancer Research 2026 Open access

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Authors: M Casado Martín, Álvaro Rodríguez-Lescure, Cristina Reboredo, Eveline Chen, Manuel Ruiz-Borrego, Ana Santaballa Bertrán, C A Wanda Rodríguez, Noelia Martínez Jáñez, Emilio Alba, Kevin Tran, Ignacio Peláez Fernández, Isabel Álvarez
+14 more Miguel A. Seguí, Alberto De La Cruz, Vicente Valero, Antonio Antón-Torres, Raquel Andrés, Kepa Amillano, José J. Ponce-Lorenzo, Severina Domínguez Fernández, Jesús Herránz, Raúl Rincón, Rosalía Caballero, Angel Guerrero-Zotano, Federico Rojo, W. Fraser Symmans
DOI: 10.1158/1078-0432.ccr-26-0177
Cited by: 1
References: 36

Abstract

PURPOSE: To independently validate that low endocrine transcriptional activity measured by the sensitivity to endocrine therapy (SETER/PR) index in hormone receptor-positive (HR+) breast cancer predicts benefit from dose-dense paclitaxel chemotherapy within a second prospective-retrospective biomarker study. EXPERIMENTAL DESIGN: We conducted a blinded, prospective-retrospective biomarker analysis within the GEICAM/9906 trial (NCT00129922), which compared adjuvant 5-fluorouracil, epirubicin, and cyclophosphamide (FEC) followed by weekly paclitaxel (P) versus six cycles of FEC in lymph node-positive breast cancer. The SETER/PR index was measured in all available HR+/HER2- tumor RNA samples using a prespecified cut point (

Fields of Study & Subjects

Breast Cancer Treatment Studies Estrogen and related hormone effects Advanced Breast Cancer Therapies

Publication details

Journal / source
Clinical Cancer Research
Publisher
American Association for Cancer Research (AACR)
Volume
32
Issue
17
Pages
3870–3879
Publication date
26 May 2026
Language
EN