Non-inferiority of local control and comparable toxicity of intensity-modulated radiotherapy with simultaneous integrated boost in breast cancer: 5-year results of the IMRT-MC2 phase III trial: IMRT-SIB is non-inferior to 3-D-CRT-seqB in RT for BC patients
Mené en Allemagne entre 2011 et 2015 sur 502 patientes atteintes d'un cancer du sein (durée médiane de suivi : 62 mois), cet essai randomisé multicentrique de phase III évalue la non-infériorité, du point de vue du taux de contrôle local et des résultats esthétiques, d'une radiothérapie fractionnée avec modulation d'intensité et boost intégré par rapport à une radiothérapie conformationnelle 3D avec boost séquentiel
Purpose: The IMRT-MC2 trial was conducted to demonstrate non-inferiority of conventionally fractionated intensity-modulated radiotherapy with simultaneous integrated boost (IMRT-SIB) to 3-D-conformal radiotherapy with sequential boost (3-D-CRT-seqB) for adjuvant breast radiotherapy. Methods and Materials: A total of 502 patients were randomized between 2011 and 2015 for the prospective, multicenter, phase-III-trial (NCT 01322854). 5-year results of late toxicity (LENT-SOMA), overall survival, disease-free survival, distant disease-free survival, cosmesis (Harvard scale) and local control (non-inferiority margin at hazard ratio of 3.5) were analyzed after a median follow-up of 62 months. Results: The 5-year LC rate for the IMRT-SIB arm was non-inferior to the control arm (98.7% vs. 98.3%, respectively; HR 0.582, 95%-CI: [0.119-2.375], p=0.4595). Furthermore, there was no significant difference in overall survival (97.1% versus 98.3%, respectively; HR 1.235, 95%-CI: [0.472-3.413], p=0.6697), disease-free survival (95.8% versus 96.1%, respectively; HR 1.130, 95%-CI: [0.487-2.679], p=0.7758) and distant disease-free survival (97.0% versus 97.8%, respectively; HR 1.667, 95%-CI: [0.575-5.434], p=0.3601). After 5 years, late toxicity evaluation and cosmetic assessment further showed no significant differences between treatment arms. Conclusion: The 5-year results of the IMRT-MC2 trial provide strong evidence, that the application of conventionally fractionated simultaneous integrated boost irradiation for breast cancer patients is both safe and effective with non-inferior local control compared to 3-D-conformal radiotherapy with sequential boost.
International Journal of Radiation Oncology, Biology, Physics 2023