The breast cancer working group (BCWG) of the Groupe Européen de Curiethérapie (GEC)-ESTRO has existed for 20 years and we are delighted to have continued to meet challenges and achieve innovations in breast brachytherapy.

Hence, it is with pleasure that we report here the recent and current highlights.

• First, last year, the updated results of the phase III prospective randomised trial in which irradiation of the whole breast was compared with that of part of the breast were published in The Lancet Oncology (Strnad V et al., Lancet Oncol. 2023;24:262-272). The BCWG is proud to publish the first long-term oncological outcome and late toxicity results. These confirm that accelerated partial-breast irradiation (APBI) performed through multicatheter interstitial brachytherapy represents an excellent and safe irradiation technique that offers a short and convenient adjuvant treatment for patients with low-risk breast cancers.
• Second, the BCWG is involved in the development of new APBI approaches that are mainly based on a very accelerated irradiation that enables the completion of adjuvant breast irradiation in three or two days or even one day. The BCWG reported during an oral communication in the 2023 American Society for Radiation Oncology (ASTRO) meeting in San Diego, USA, the results of a multicentre international retrospective study named “very accelerated partial-breast irradiation (vAPBI) in one or two days: late toxicity and early oncological outcomes of the GEC-ESTRO cohort”. The presented results showed that vAPBI seemed to be a safe and efficient irradiation technique with no differences in terms of side effects or oncological outcomes (median follow-up: four years) between two- and one-day regimens.

On the subject of APBI/vAPBI, the BCWG also published several letters to the editor in response to relevant published manuscripts (Int J Radiat Oncol Biol Phys. 2021;110:907-908; Int J Radiat Oncol Biol Phys. 2022;113:474-475).

• Third, the BCWG is deeply involved in the promotion of second conservative treatment (second CT) for patients who experience a second ipsilateral breast cancer malignancy (second iBTM). In 2021, the BCWG published in the Red Journal the results of an international propensity score-matched cohort analysis that compared salvage mastectomy with second conservative treatment (Int J Radiat Oncol Biol Phys. 2021;110(2):452-461). In 2023, the BCWG wished to propose that the selection criteria be analysed for consideration of a second CT in the case of a second iBTM. We published in the Red Journal the largest cohort of patients who had undergone a second CT with multi-catheter interstitial brachytherapy-based tumour bed re-irradiation (>500 patients) and provided a rigorous prognostic factor analysis that led to the recommendation of a TAM score (T: time interval between breast surgeries one and two; A: APBI classification; M: molecular classification) as a strong prognostic factor for oncological outcome specifically for distant metastasis-free survival.

In the frame of the second CT, the BCWG also published several letters to the editor in response to relevant published manuscripts (Eur J Cancer. 2021;159:224-226; Breast Cancer Res Treat. 2021;187:105-112; J Breast Cancer. 2021;24:356-357; Ann Oncol. 2022;33:1088).

Currently, the BCWG is working on the following projects:

• breast brachytherapy educational paper

Marta Gimeno Morales (University of Navarre, Spain) and colleagues submitted to the Journal of Contemporary Brachytherapy a manuscript entitled “Post- versus intra-operative implant for breast cancer interstitial brachytherapy: how to choose?” In this educational manuscript, the BCWG presents the two multicatheter interstitial brachytherapy techniques that can be offered: intra-operative or post-operative. This article aimed to summarise currently available data about these two brachytherapy approaches to breast cancer and to give the readers (breast surgeons, radiation and medical oncologists and patients) clear information to help in the decision-making process regarding the best implant technique to use.

• GEC-ESTRO BCWG APBI “grey zone” recommendations 

Cristina Gutiérrez, Csaba Polgár (Catalan Institute of Oncology, Spain) and BCWG colleagues are preparing a manuscript that aims to refine the indications for the use of APBI by focusing on so-called “grey zone” points instead of presenting an update of standard recommendations that have already been published by other colleagues from international radiation therapy societies. In this manuscript, a specific analysis is proposed of debatable indications for the use of the technique, such as the young age of the patient, a resection margin of less than 2mm, N1mic and N1a axillary lymph node status, invasive lobular carcinoma, lymphovascular involvement and the presence of triple-negative or human epidermal growth factor receptor-2 (HER2)-positive tumours.

• an update of the vAPBI Phase I/II GEC-ESTRO prospective trial

Jose-Luis Guinot (Valencian Institute of Oncology, Spain) and colleagues published the feasibility and early results of the phase I/II multicentre trial of the use of vAPBI(Brachytherapy, 2021;20:332-338). They are preparing a manuscript on the five-year results of the trial on behalf of the GEC-ESTRO breast working group 2.

The results of the vAPBI (one- or two-day regimen) BCWG cohort will be submitted soon.

• international Delphi consensus for second ipsilateral breast cancer event management

In 2023, the BCWG initiated an international collaborative project to propose the production of a Delphi consensus on the management of a second iBTM. This project includes radiation oncologists and breast surgeons from the European Union and the USA, who belong to nine international scientific societies (GEC-ESTRO, ESTRO, ASTRO, the Association of Breast Surgery, the American Society of Breast Surgeons, the Society of Surgical Oncology, the European Society of Surgical Oncology, the European Breast Cancer Research Association of Surgical Trialists, and the European Association of Societies of Aesthetic Plastic Surgery).

 

The BCWG of GEC-ESTRO is deeply involved in and dedicated to the promotion of multicatheter interstitial brachytherapy. With APBI, vAPBI, and avoidance of breast mutilation in case of local relapse, the BCWG is contributing to a shift in paradigms in breast cancer treatment.

 

December 6, 2023

Jean-Michel Hannoun-Levi MD, PhD

Chairman of BCWG of GEC-ESTRO