Non-inferior local control of IMRT-SIB compared to 3D-CRT-seqB - 5-year results of a phase III trial
PO-1262
Abstract
Non-inferior local control of IMRT-SIB compared to 3D-CRT-seqB - 5-year results of a phase III trial
Authors: Tobias Forster1, Matthias Felix Häfner1, Nathalie Arians1, Laila König1, Semi Ben Harrabi1, Ingmar Schlampp1, Fabian Weykamp1, Eva Meixner1, Kristin Lang1, Vanessa Heinrich2, Nicola Weidner2, Johannes Hüsing3, Markus Wallwiener4, Michael Golatta4, Andre Hennigs4, Jörg Heil4, Holger Hof5, David Krug6, Jürgen Debus1, Juliane Hörner-Rieber1
1Heidelberg University, Radiooncology, Heidelberg, Germany; 2Tübingen University, Radiooncology, Tübingen, Germany; 3Heidelberg University, Division of Biostatistics, Heidelberg, Germany; 4Heidelberg University, Gynecology, Heidelberg, Germany; 5Strahlentherapie Rhein-Pfalz, Radiooncology, Neustadt, Germany; 6Kiel University, Radiooncology, Kiel, Germany
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Purpose or Objective
The IMRT-MC2 trial was conducted to demonstrate non-inferiority of conventional 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.
Material and Methods
A total of 502 patients were randomized between 2011 and 2015 for the prospective, multicenter, randomized phase-III-trial (NCT 01322854). 5-year results of late toxicity (LENT-SOMA), overall survival, disease-free survival, distant cancer-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 cancer-free survival (97.0% versus 97.8%, respectively; HR 1.667, 95%-CI: [0.575-5.434], p=0.3601). After 5 years, the late toxicity and cosmetic assessment 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 IMRT-SIB for breast cancer patients is both safe and effective with non-inferior local control compared to 3-D-CRT-seqB.