S297
Clinical - Breast
ESTRO 2026
covered the two different clinical scenarios of this randomized trial: either TAS followed by ALND and regional nodal irradiation (RNI) excluding the dissected axilla as a target volume (arm A) or TAS followed by RNI including the full axilla (arm B). Material/Methods: All centers had to provide a facility questionnaire, send CT-scans of the dummy cases with contoured organs at risk (OAR) and target volumes according to ESTRO guideline, and a planning review form containing relevant planning information. Dummy runs were evaluated by two out of four radiation oncology experts of the study group. In case of dis-agreement between both experts, a third one was involved. Feedback to all centers and an agreement with each center had to be achieved, before the first patient could be enrolled. Here we present the data of the dummy runs of all 50 centers in Europe. Results: Out of 50 centers, 2 centers did not submit their files. Out of the remaining 48 centers, 8 and 14 showed major deviations in defining CTVp and CTVn in arm A, respectively, and 7 and 13 in arm B, although contouring guidelines had been defined. With respect to OARs the dominant deviation was the definition of the cranial border of the heart, being initially not correct in 15 centers. Six and 10 centers had minor deviations to fulfil dose criteria for ipsilateral lung and heart. In total, rejection and major revision was necessary in 18 (38%) and 17 (35%) of the centers for arm A and arm B, respectively. After one to three revisions the dummy runs were accepted without any deviations for 12 centers and with acceptable minor deviation for 34 centers. Two centers provided no revised plan.
Poster Discussion 3298
Quality Assurance of Radiotherapy in the TAXIS- Trial (OPBC-03): Experiences with Dummy Run Procedures and Consequences for Future Randomized Trials Guido Henke 1,2 , Anna-Lena Eberhardt 3,4 , Frank Zimmermann 3,4 , Daniel Zwahlen 5 , Zoltan Matrai 6 , Christoph Tausch 7 , Giacomo Montagna 8 , Florian Fitzal 9,10 , Michael Gnant 9 , Thomas Ruhstaller 3,11 , Jelena Winkler 12,3 , Simone Muenst 3,13 , Andreas Mueller 14,15 , Loic Lelièvre 16 , Joerg Heil 17 , Christian Kurzeder 12,3 , Daniel Egle 18 , Akos Savolt 19 , Martin Heidinger 12,3 , Michael Knauer 11 , Ludwig Plasswilm 2 , Stefanie Hayoz 14 , Guenther Gruber 20 , Walter Paul Weber 12,3 1 Department of Radiation Oncology, Cantonal hospital Münsterlingen, Münsterlingen, Switzerland. 2 Department of Radiation Oncology, HOCH, Cantonal Hospital St. Gallen, St. Gallen, Switzerland. 3 Faculty of Medicine, University of Basel, Basel, Switzerland. 4 Clinic of Radiation Oncology, University Hospital Basel, Basel, Switzerland. 5 Clinic of Radiation Oncology, Canton Hospital Winterthur, Winterthur, Switzerland. 6 Hamad Medical Corporation, Dept of Oncoplastic Breast Surgery, Doha, Qatar. 7 Breast Center Zurich, Hirslanden Zürich, Zurich, Switzerland. 8 Breast Service, Department of Surgery, Memorial Sloan Kettering Cancer Center, New York, USA. 9 Comprehensive Cancer Center, Medical University Vienna, Vienna, Austria. 10 Department of Surgery, Medical University Vienna, Vienna, Austria. 11 Tumor- and Breast Center Eastern Switzerland, TBZO, St. Gallen, Switzerland. 12 Breast Center, University Hospital Basel, Basel, Switzerland. 13 Institute of Medical Genetics and Pathology, University Hospital Basel, Basel, Switzerland. 14 Swiss Group for Clinicl Cancer Research, SAKK, Bern, Switzerland. 15 Breast Center, Cantonal Hospital Winterthur, Winterthur, Switzerland. 16 Breast Center, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland. 17 Department of Obstetrics & Gynecology, Heidelberg University Hospital, Heidelberg, Germany. 18 Department of Gynecology and Gynecological Oncology, Medical University of Innsbruck, Innsbruck, Austria. 19 National Institute of Oncology, NIO, Budapest, Hungary. 20 Clinic of Radiation Oncology, Hirslanden Zurich, Zurich, Switzerland Purpose/Objective: The TAXIS trial was designed to investigate if axillary radiotherapy can replace axillary lymph node dissection (ALND) in patients with clinically node- positive breast cancer, detected by imaging or palpation in the upfront surgery setting or in case of residual disease after NACT, who underwent tailored axillary surgery (TAS). The obligatory dummy run as part of the intensive quality assurance program
Conclusion: For oncological trials, where radiotherapy may have an impact on clinical outcome, a dummy run including full treatment planning should be conducted to homogenize irradiation. In subsequent publications, a precise explanation of target volumes, technique and dose constraints of radiotherapy used within the trial is necessary to guarantee a safe transfer into clinical routine. Keywords: Breast Cancer, Radiotherapy, Quality assurance
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