ESTRO 2023

Session Item

Monday

May 15

11:40 - 12:40

Plenary Hall

Highlights of Proffered Papers - Latest clinical trials

Chair: , United Kingdom;

Chair: , Switzerland

Session Code: 3290

Session Type: Proffered Papers

Track: Interdisciplinary

12:00 - 12:10

Accelerated partial breast irradiation: 10-year results of a randomized GEC-ESTRO phase III trial

, Germany

Presentation Number: OC-0830

Abstract

Abstract Title:

Accelerated partial breast irradiation: 10-year results of a randomized GEC-ESTRO phase III trial

Authors:

Vratislav Strnad¹, Csaba Polgár², Oliver Ott³, Guido Hildebrandt⁴, Daniela Kauer-Dorner⁵, Hellen Knauerhase⁴, Tibor Major⁶, Jaroslaw Lyczek⁷, Jose Luis Guinot⁸, Cristina Gutierrez Miguelez⁹, Pavel Slampa¹⁰, Peter Niehoff¹¹, Michael Allgäuer¹², Kristina Lössl¹³, Bülent Polat¹⁴, Rainer Fietkau¹⁵, Annika Schlamann¹⁶, Alexandra Resch⁵, Anna Kulik¹⁷, Leo Arribas¹⁸, Ferran Guidea⁹, Christine Gall¹⁹, Wolfgang Uter¹⁹

¹University Hospital Erlangen, Dept. of Radiation Oncology, Erlangen, Germany; ²National Institute of Oncology Budapest, Dept.of Radiation Oncology, Budapest, Hungary; ³University Hospital Erlangen, Dept. of Radiation Oncology, Erlangen, Germany; ⁴University Hospital Rostock, Dept. of Radiation Oncology, Rostock, Germany; ⁵University Hospital AKH, Dept. of Radiation Oncology, Vienna, Austria; ⁶National Institute of Oncoogy Budapest, Dept. of Radiation Oncology, Budapest, Hungary; ⁷Podkarpacki Hospital Cancer Center , Dept. of Radiation Oncology, Brzozów, Poland; ⁸Valencian Institute of Oncology , Dept. of Radiation Oncology, Valencia, Spain; ⁹Catalan Institute of Oncology , Dept. of Radiation Oncology, Barcelona, Spain; ¹⁰Masaryk Memorial Cancer Institute , Dept. of Radiation Oncology, Brno, Czech Republic; ¹¹Sana Hospital Offenbach, Dept. of Radiation Oncology, Offenbach, Germany; ¹²Hospital Barmherzige Brüder Regensburg, Dept. of Radiation Oncology, Regensburg, Germany; ¹³University Hospital Bern, Inselspital, Dept. of Radiation Oncology, Bern, Switzerland; ¹⁴University Hospital Würzburg, Dept.of Radiation Oncology, Würzburg, Germany; ¹⁵University Hospital Erlangen, Dept.of Radiation Oncology, Erlangen, Germany; ¹⁶University Hosital Leipzig, Dept.of Radiation Oncology, Leipzig, Germany; ¹⁷Instytut im Marii Skłodowskej , Dept. of Radiation Oncology, Warsaw, Poland; ¹⁸Valencian Institute of Oncology, Depr. of Radiation Oncology, Valencia, Spain; ¹⁹University Erlangen-Nuremberg, Department of Medical Informatics, Biometry and Epidemiology, Erlangen, Germany

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Purpose or Objective

Different techniques exist for the delivery of accelerated partial breast irradiation (APBI) for appropriately selected patients with early breast cancer after breast-conserving surgery (BCS). The long-term 10y.-results of a Phase 3 trial evaluating the non-inferiority of APBI using multicatheter brachytherapy compared to whole-breast irradiation (WBI) are presented.

Material and Methods

We randomized patients aged ≥40 years with low risk invasive breast cancer and ductal carcinoma in-situ after BCS to receive either 50 Gy WBI with tumor bed boost of 10 Gy or APBI using multicatheter brachytherapy. The primary endpoint was local recurrence rate in the “as-treated” population. Secondary endpoints were overall survival, disease-free survival, cumulative incidence of regional recurrence and distant metastasis, incidence and severity of acute and late side effects, cosmesis. The trial is registered with ClinicalTrials.gov, NCT00402519.

Results

Between 2004 and 2009, 1184 participants with early stage breast cancer were randomly assigned to receive either WBI with boost or APBI using interstitial multicatheter brachytherapy. Median follow-up of patients was 10.4 years. The cumulative incidence of local recurrence at 10 years was 1.58% (95% CI: 0.37; 2.8%) in the WBI and 3.51% (95% CI: 1.99; 5.03%) in the APBI arm (difference 1.93% (95% CI: -0.018; 3.87, p=0.074). 10-year disease-free survival was 87.95% (95%CI: 85.1 – 90.91%) with WBI and 84.89% (95%CI: 81.97 – 87.91%) with APBI (difference -3.06%, 95% CI: -7.22;1.09%; p=0.18). 10-year overall survival was 89.5% (95% CI: 86.9–92.2%) in WBI-treated and 90.5% (95% CI: 88.1–92.9%) in APBI-treated patients (difference 1·95% CI: -2·66–4·56; p=0·5). Finally, the patients in APBI arm showed significantly lower incidence of treatment-related late-side events > grade 2 (p=0.021).

Conclusion

The efficacy of adjuvant APBI using multicatheter brachytherapy after breast conserving surgery for early breast cancer is similar to adjuvant WBI with tumor bed boost and is associated with lower incidence of late side effects.