Local treatment for HER2-positive or triple negative second ipsilateral breast cancer event: A propensity score-matched analysis of the GEC-ESTRO database

Hannoun-Levi JM, Gal J, Weltens C, Smanyko V, Kauer-Domer D, Pasquier D, Lemanski C, Racadot S, Houvenaeghel G, Guix B, Belliere-Calandry A, Loessl K, Polat B, Gutierrez C, Galalae R, Polgar C, Schiappa R, Strnad V (2026)

Publication Type: Journal article

Publication year: 2026

Journal

The Breast Elsevier

Book Volume: 89

Article Number: 104895

DOI: 10.1016/j.breast.2026.104895

Abstract

Purpose: Second breast conserving treatment (2ndBCT) has emerged as an option for patients with low-risk second ipsilateral breast cancer event (2ndiBCE) after prior breast BCT combining lumpectomy and irradiation. However, HER2-positive (HER2+) and triple-negative (TN) subtypes are considered poor candidates for 2ndBCT. We evaluated oncologic outcomes after 2ndBCT versus mastectomy in high-risk 2ndiBCE. Methods and materials: We performed a propensity score-matched cohort study of patients diagnosed with 2ndiBCE between 1995 and 2017. Data were collected from 15 centers across seven European countries. Patients underwent mastectomy or lumpectomy plus Multicatheter-interstitial brachytherapy (MIB). One-to-one matching used ten clinicopathologic variables. The primary endpoint was 5-year overall survival (OS). Secondary endpoints included 5-year cumulative incidence of third breast events, regional relapse, distant metastasis, disease-free survival (DFS) and cause-specific survival (CSS). Results: Among 1327 patients (Mastectomy 945; 2ndBCT 382), 241 were matched (Mastectomy versus 2ndBCT): HER2+ 70/62 and TN 55/54. Median tumour size (mm) for mastectomy versus 2ndBCT was 17/13 in HER2+ and 13/12 in TN. Median follow-up was 79.9 and 80.5 months for HER2+ and TN, respectively, without group differences. No statistical differences in 5-year OS were observed between mastectomy and 2ndBCT (HER2+: 85% vs 79%, p = 0.85; TN: 89% vs 81%, p = 0.4). Similarly, the secondary endpoints were also comparable between groups. Conclusion: This first matched comparison of mastectomy and 2ndBCT with MIB in patients with HER2+ and TN tumours did not identify clear differences in efficacy. Given the limited sample size, 2ndBCT may warrant consideration in selected patients seeking breast preservation.

Authors with CRIS profile

Vratislav Strnad Department of Radiation Oncology

Involved external institutions

EBG MedAustron GmbH AT Austria (AT) University of Côte d'Azur / Université Côte d'Azur FR France (FR) University Hospital Leuven (UZ) / Universitaire ziekenhuizen Leuven BE Belgium (BE) Országos Onkológiai Intézet / National Institute of Oncology HU Hungary (HU) Medizinische Universität Wien AT Austria (AT) LILLE 1 University - Science and Technology FR France (FR) Institut de Recherche en Cancérologie de Montpellier (IRCM) FR France (FR) Centre Léon-Bérard (UNICANCER) FR France (FR) Institute Paoli-Calmettes FR France (FR) Hospital Clínic de Barcelona ES Spain (ES) Centre Jean-Perrin (UNICANCER) FR France (FR) Inselspital, Universitätsspital Bern CH Switzerland (CH) Julius-Maximilians-Universität Würzburg DE Germany (DE) Hospital del Mar ES Spain (ES)

How to cite

APA:

Hannoun-Levi, J.M., Gal, J., Weltens, C., Smanyko, V., Kauer-Domer, D., Pasquier, D.,... Strnad, V. (2026). Local treatment for HER2-positive or triple negative second ipsilateral breast cancer event: A propensity score-matched analysis of the GEC-ESTRO database. The Breast, 89. https://doi.org/10.1016/j.breast.2026.104895

MLA:

Hannoun-Levi, J. M., et al. "Local treatment for HER2-positive or triple negative second ipsilateral breast cancer event: A propensity score-matched analysis of the GEC-ESTRO database." The Breast 89 (2026).

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