ESTRO 2022 - Abstract Book

S652

Abstract book

ESTRO 2022

and 92.1% [95% CI 83.7–100], respectively. Late toxicity (CTCAE-V3) was assessed in 51 patients (86%) with a median follow- up of 13 years. Fifteen presented grade 2 fibrosis (29.4%), 8 (15.7%) had telangiectasia, and 1 radiodermatitis.

Conclusion This combined treatment provided high long-term local control rates with limited side-effects.

PD-0740 Danish Breast Cancer Group Skagen Trial 1: A report on annual trial participation

L. Bech Jellesmark Thorsen 1 , I. Mjaaland 2 , M. Hjelstuen 2 , E. Hugger Jakobsen 3 , M. Berg 3 , T. Lörincz 4 , I. Jensen 4 , U. Kasti 5 , M. Hasler 5 , M. Holck Nielsen 6 , E. Laugaard Lorentzen 7 , S. Aziz-Jowad Al-Rawi 8 , M.M. Bruun Nielsen 8 , M. Krause 9 , A. Linge 10 , C. Kamby 11 , K. Boye 11 , E. Svitzer Yates 1 , B. Vrou Offersen 1,12 1 Aarhus University Hospital, Department of Oncology, Aarhus, Denmark; 2 Stavanger University Hospital, Department of Oncology, Stavanger, Norway; 3 Vejle Hospital, Department of Oncology, Vejle, Denmark; 4 Aalborg University Hospital, Department of Oncology, Aalborg, Denmark; 5 Sørlandet Hospital, Department of Oncology, Kristiansand, Norway; 6 Odense University Hospital, Department of Oncology, Odense, Denmark; 7 Odense University Hospital, Laboratory of Radiation Physics, Odense, Denmark; 8 Zealand University Hospital, Department of Clinical Oncology and Palliative Care, Næstved, Denmark; 9 University Hospital and Faculty of Medicine Carl Gustav Carus; Technische Universität Dresden; German Cancer Consortium Dresden; Helmholtz-Zentrum Dresden-Rossendorf; National Center for Tumor Diseases, Dresden; and German Cancer Research Center, Heidelberg, Germany., Department of Radiation Oncology and OncoRay Center,, Dresden, Germany; 10 University Hospital and Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden; German Cancer Consortium Dresden; Helmholtz-Zentrum Dresden-Rossendorf; National Center for Tumor Diseases, Dresden; and German Cancer Research Center, Heidelberg, Germany., Department of Radiation Oncology and OncoRay Center, Dresden, Germany, Dresden, Germany; 11 Rigshospitalet, Department of Oncology, Copenhagen, Denmark; 12 Aarhus University Hospital, Department of Experimental Clinical Oncology, Aarhus, Denmark Purpose or Objective Clinical trials are essential to improve cancer treatment. Trials rely on wide-ranging patient (pt) participation to gain adequate sample sizes and externally applicable results. The Danish Breast Cancer Group (DBCG) develops national guidelines for breast cancer therapy, and this is preferably through clinical trials. During 2015-2021 moderately hypofractionated adjuvant loco-regional breast cancer (BC) radiation therapy (RT) was tested in an international trial, the DBCG SKAGEN Trial 1, testing 50Gy/25 fr (standard) versus 40Gy/15fr (experimental). The trial inclusion criteria were broad, thus any pt with indication for loco-regional RT (LR-RT) for unilateral early high-risk BC with no prior cancer and willing/able to participate in the 10-year follow up was a candidate.Recently, the inclusion of pts in trials may have been particularly challenged due to difficulties imposed by the COVID 19 pandemic. Hitherto, the DBCG has had no evidence- based knowledge about trial participation rates (TPR). These are important for evaluating the applicability of the trial results and planning of future RT trials. We present annual trial participation rates during the inclusion period. Materials and Methods The international DBCG SKAGEN Trial 1 randomized patients from 2015 to July 1 st 2021, and the 17 participating institutions from 7 countries accrued 2,963 patients. Eight of these institutions accruing 2,184 pts in all delivered data on the total number of pts treated with LR-RT during the inclusion period. We calculated annual TPRs per institution and overall as TPR (number pts enrolled per year/ number pts treated with LR-RT per year). Results From 6,929 pts receiving LR-RT, 2,184 pts were enrolled, corresponding to an overall TPR of 31.5% (figure 1). In all eight institutions, accrual was running from 2016 (figure 2). From 2016, the average single institution TPR per year ranged from 14.4% to 50.4%. Annual TPRs varied with time: most institutions experienced a modest decline in TPR during 2019-2020, while in 2021 TPR seemed to stabilize. In one institution, accrual was terminated during 2020 due to COVID 19 related restrictions.