A comparison of a brachytherapy and an external beam radiotherapy boost in breast-conserving therapy for breast cancer: local and any recurrences

  • Isabelle Kindts
  • Karolien Verhoeven
  • Annouschka Laenen
  • Melissa Christiaens
  • Hilde Janssen
  • Aline Van der Vorst
  • Erik Van Limbergen
  • Caroline Weltens
Original Article



Adding a tumour bed boost to whole-breast irradiation in breast-conserving therapy reduces local recurrence rates. The purpose of the present study was to investigate whether the boost technique influences the magnitude of the effect.


Patients treated with breast-conserving therapy for invasive breast cancer between 2000 and 2007 were included in the analysis. Three groups were considered according to the applied boost technique: electrons, brachytherapy or photons. The endpoints were local recurrence and any recurrence. Cox regression models were used and correction for the confounders in the association between boost technique and outcome was performed using multivariable models.


1879 tumours were included in the analysis. 1448 tumours (77.1%) were treated with an electron boost, 334 (17.8%) with a brachytherapy boost and 97 (5.2%) with a photon boost. Median follow-up was 13.1 years. The 10-year local recurrence rate was 2.2%. In multivariable analysis with correction for age, pathological Tumour or Node stage (pT, pN), chemotherapy and hormonal therapy, there was no significant difference between the three groups for the local recurrence risk (p = 0.89). 10-year any recurrence rate was 10.8%. In multivariable analysis with correction for age, pT, pN, resection margins, radiotherapy, year of diagnosis, chemotherapy and hormonal therapy, there was no significant difference between the brachytherapy group and the electron group or the photon group (p = 0.11 and p = 0.28, respectively). The photon group had more recurrences compared to the electron group (Hazard Ratio 1.81, 95% Confidence Interval 1.12; 2.92, p = 0.02).


The local recurrence risk reduction of the tumour bed boost in breast-conserving therapy is not influenced by the applied boost technique.


Breast cancer Breast-conserving therapy Boost technique Recurrence Radiotherapy 

Ein Vergleich von Brachytherapie und perkutanem Strahlentherapie-Boost nach brusterhaltender Therapie bei Brustkrebs: Lokalrezidive und alle Rezidive



Mit einem zusätzlichen Boost auf das Tumorbett wird bei Bestrahlung der ganzen Brust im Rahmen der brusterhaltenden Therapie eine Reduktion der lokalen Rezidivrate erreicht. Das Ziel der vorliegenden Studie war es, zu untersuchen, ob die Boost-Technik das Ausmaß des Effekts beeinflusst.


In die Analyse wurden Patientinnen, die zwischen 2000 und 2007 mit brusterhaltender Therapie bei einem invasiven Brustkrebs behandelt wurden, einbezogen. Je nach verwendeter Boost-Technik wurden drei verschiedene Gruppen unterschieden: Elektronen, Brachytherapie oder Photonen. Die Endpunkte waren das Auftreten eines lokalen Rezidivs und jedes Rezidiv. Benutzt wurden Cox-Regressions-Modelle. Eine Korrektur der Störfaktoren in Zusammenhang zwischen Boost-Technik und Outcome erfolgte mit multivariablen Modellen.


In die Analyse wurden 1879 Tumoren inkludiert: 1448 Tumoren (77,1 %) wurden mit einem Elektronen-Boost, 334 (17,8 %) mit Brachytherapie und 97 (5,2 %) mit einem Photonen-Boost behandelt. Die mediane Nachbeobachtungszeit betrug 13,1 Jahre. Die 10-Jahres-Lokalrezidivrate lag bei 2,2 %. In multivariablen Analysen unter Berücksichtigung von Alter, pathologisches Tumor oder Lymfknot (pT oder pN), Chemotherapie und hormoneller Therapie gab es keinen signifikanten Unterschied hinsichtlich des Lokalrezidivrisikos (p = 0,89) zwischen den drei verschiedenen Behandlungsgruppen. Die 10-Jahres-Rezidivrate jeglicher Art lag bei 10,8 %. In der multivariablen Analyse unter Berücksichtigung von Alter, pT, pN, Resektionsrändern, Strahlentherapie, Zeitpunkt der Diagnosestellung, Chemotherapie und hormoneller Therapie gab es keinen signifikanten Unterschied zwischen der Brachytherapie- und der Elektronen- oder der Photonentherapie-Gruppe (jeweils p = 0,11 und p = 0,28). In der Photonentherapie-Gruppe traten im Vergleich zur Elektronen-Gruppe mehr Rezidive auf (Hazard Ratio 1,81; 95 %-Konfidenzintervall 1,12; 2,92, p = 0,02).


Bei Anwendung des Tumorbett-Boosts in der brusterhaltenden Therapie wird die Verringerung des Lokalrezidivrisikos nicht durch die benutzte Boost-Technik beeinflusst.


Brustkrebs Brusterhaltende Therapie Boost-Technik Rezidiv Strahlentherapie 


Conflict of interest

I. Kindts, K. Verhoeven, A. Laenen, M. Christiaens, H. Janssen, A. Van der Vorst, E. Van Limbergen and C. Weltens declare that they have no competing interests.


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  • Isabelle Kindts
    • 1
    • 2
  • Karolien Verhoeven
    • 3
  • Annouschka Laenen
    • 4
  • Melissa Christiaens
    • 2
  • Hilde Janssen
    • 1
    • 2
  • Aline Van der Vorst
    • 2
  • Erik Van Limbergen
    • 1
    • 2
  • Caroline Weltens
    • 1
    • 2
  1. 1.Department of Oncology, Experimental Radiation OncologyKU Leuven—University of LeuvenLeuvenBelgium
  2. 2.Department of Radiation OncologyUniversity Hospitals LeuvenLeuvenBelgium
  3. 3.Department of Radiation Oncology (MAASTRO), GROW—School for Oncology and Developmental BiologyMaastricht University Medical CentreMaastrichtThe Netherlands
  4. 4.Leuven Biostatistics and Statistical Bioinformatics Centre (L-Biostat)KU Leuven UniversityLeuvenBelgium

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