ESTRO38 Congress Report

Brachytherapy

3. 2 nd Conservative Treatment for 2 nd Ipsilateral Breast Tumor Event: Mature results from GEC-ESTRO Breast Cancer WG (E38-1734) JMHannoun-Levi 1 , D Kauer-Domer 2 , B Guix3, J Gal4, R Schiappa4, C Polgar5, C Gutierrez6, P Niehoff7, R Galalae8, K Loessl9, B Polat10, G Kovacs 11 , E Van Limbergen12, V Strnad13 On behalf of the BCWG of the GEC-ESTRO 1 Department of Radiation Oncology, Antoine Lacassagne Cancer Center, University of Cote d’Azur, Nice France, 2 Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria, 3 Department of Radiation Oncology, Institute Medic Onco Radiotherapia, Barcelona, Spain, 4 Biostatistics’ Unite, Antoine Lacassagne Cancer Center, University of Cote d’Azur, Nice, France, 5 Department of Radiation Oncology, National Institute of Oncology in Budapest, Hungary, 6 Department of Radiation Oncology, Catalan Institute of Oncology, Barcelona, Spain, 7 Department of Radiation Oncology, University Hospital, Offenbach, Germany 8 Department of Radiation Oncology, University of Kiel, Kiel, Germany, 9 Department of Radiation Oncology, University Hospital Berne, Berne, Switzerland, 10 Department of Radiation Oncology, University of Wurzburg, Wurzburg, Germany, 11 Department of Radiation Oncology, University of Lubeck, Lubeck, Germany, 12 Department of Radiation Oncology, Experimental Radiotherapy Laboratory. Leuven, Belgium, 13 Department of Radiation Oncology, University Erlangen-Nuremberg, Erlangen, Germany

Context of the study Until now, salvage mastectomy is considered the standard treatment for local recurrence of breast cancer (2 nd Ipsilateral Breast Tumor Event). For the past decade, the GEC-ESTRO Breast Cancer Working Group has been working to develop a second conservative treatment for patients with a 2 nd IBTE. Overview of abstract In 2013. the GEC-ESTRO BCWG published the oncological results and late side effects of treatment of 2 nd IBTE with lumpectomy plus re-irradiation of the tumor bed using multicatheter interstitial brachytherapy. This analysis focused on 217 patients with a median follow-up of 3.9 years. The present study reports moremature results from a larger cohort of 331 patients with a longer follow-up of 72 months. The rate of 3 rd IBTE-free survival at 6 years for the whole cohort was excellent (93%); in “low-risk” breast cancer in the GEC-ESTRO classification, this rate was almost 100%. The rate of late severe side effects was about 10%.

What were the three main findings of your research? As far as we know, the GEC-ESTRO BCWG has reported the largest cohort of 2nd conservative treatment for 2ndIBTE. With a 6-year median follow-up, we provide consistent data for 2nd conservative treatment as an attractive treatment option. What impact could your research have? In case of 2 nd IBTE, second CT combining re-lumpectomy plus APBrI represents a valid therapeutic option in terms of oncological outcome as well as toxicity profile. Patient and tumor characteristics have to be carefully evaluated and patient informed consent is crucial for the discussion of treatment choices. Is this research indicative of a bigger trend in oncology? In the frame of therapeutic de-escalation, avoiding mutilation is a key objective in cancer treatment. Reducing the psychological impact of mastectomy while keeping excellent oncological outcome contributes to improved patient quality of life.

LR: low-riskbreastcanceraccording to theGEC-ESTROAPBIclassification; IR: Intermediaterisk;HR:high-risk;3rdIBTE-FS:3rd ipsilateral breast tumorevent freesurvival;RFS:regional-freesurvival;MFS:metastatic -freesurvival;SS:specificsurvival;OS:overallsurvival.

BRACHYTHERAPY | Congress report

28