ESTRO 2022 - Abstract Book

S76

Abstract book

ESTRO 2022

Conclusion At 2-3 years’ follow-up there is no early indication that outcomes relating to arm or shoulder adverse effects are different for 26Gy/5Fr compared with the standard 15Fr regimen but definitive assessment of non-inferiority will await the formal primary analysis at 5 years.

Funding

UK NIHR HTA (09/01/47)

OC-0102 DBCG phase III randomized trial of hypo- vs standard fractionated RT in 2879 pN+ breast cancer pts

B. Offersen 1 , J. Alsner 1 , H.M. Nielsen 2 , T. Bechmann 3 , M.H. Nielsen 4 , I. Mjaaland 5 , C. Kamby 6 , C. Krkove 7 , T. Lorincz 8 , S. Al- Rawi 9 , E.B. Stoere 10 , A. Schreiber 11 , M. Krause 12 , U. Kasti 13 , L.W. Matthiessen 14 , P. Kedzierawski 15 , T. Marinko 16 , M. Luukkaa 17 , T. Skyttä 18 , M. Jensen 19 , J. Overgaard 1 1 Aarhus University Hospital, Department of Experimental Clinical Oncology, Aarhus, Denmark; 2 Aarhus University Hospital, Department of Oncology, Aarhus, Denmark; 3 Lillebaelt Hospital, Department of Oncology, Vejle, Denmark; 4 Odense University Hospital, Department of Oncology, Odense, Denmark; 5 Stavanger University Hospital, Department of Oncology, Stavanger, Norway; 6 Rigshospitalet, Copenhagen University Hospital, Department of Oncology, Copenhagen, Denmark; 7 Université Catholique de Louvain, Cliniques Universitaires St-Luc, Radiotherapy Department, Bruxelles, Belgium; 8 Aalborg University Hospital, Department of Oncology, Aalborg, Denmark; 9 Zeeland University Hospital, Department of Oncology, Naestved, Denmark; 10 UiT, The Arctic University of Norway, Department of Clinical Medicine, Tromsoe, Norway; 11 Academic Teaching Hospital Dresden-Friedrichstadt, Department of Oncology, Dresden, Germany; 12 University Hospital Carl Gustav Carus, Technische Universität Dresden, Clinic for Radiotherapy and Oncology, Dresden, Germany; 13 Hospital of Kristiansand, Department of Oncology, Kristiansand, Norway; 14 Herlev and Gentofte University Hospital, Department of Oncology, Herlev, Denmark; 15 Holycross Cancer Center, Department of Oncology, Kielce, Poland; 16 Institute of Oncology Ljubljana, Department of Oncology, Ljubljana, Slovenia; 17 Turku University Hospital, Department of Oncology, Turku, Finland; 18 Tampere University Hospital, Department of Oncology, Tampere, Finland; 19 Rigshospitalet, Copenhagen University Hospital, DBCG, Copenhagen, Denmark Purpose or Objective Adjuvant radiation therapy (RT) for node-positive early breast cancer using 50 Gy/25 fr has been Danish Breast Cancer Group (DBCG) standard since 1982. Over the last decade moderately hypofractionated breast cancer RT based on 40Gy/15fr has been increasingly used, however, not for loco-regional therapy due to concern over a higher risk of morbidity. In that scenario, the non-inferiority DBCG Skagen trial 1 was designed the hypothesis being that 40 Gy/15 fr (2.67 Gy/fr) did not result in more arm lymphedema than 50 Gy/25 fr (2.0 Gy/fr) 3 years after RT. Materials and Methods A total of 2879 patients ≥ 18 years operated for node-positive breast cancer were enrolled during 2015-21 and randomized 50 Gy/25 fr vs. 40 Gy/15 fr. All tumour-bed boosts were simultaneous integrated (SIB). The primary endpoint was ipsilateral arm lymphedema at 3 years ( ≥ 10% increase in arm circumference 15 cm proximal and/or 10 cm distal to the olecranon on the treated side compared to the contralateral arm). All target volume delineations were according to the ESTRO consensus on target volume delineation of early breast cancer. Accrual was to stop, when 3-year estimates of arm lymphedema had been reported in 1012 patients. The trial was registered with ClinicalTrials.gov, number NCT02384733. Results The 50 Gy group comprised 1442 patients (50%) and the 40 Gy group 1437 patients (50%). Median age was 58 years (range 20-86 years). Mastectomy was used in 1372 patients (48%), 1507 patients (52%) had lumpectomy, and a SIB was used in 16% of the patients.