World Congress of Brachytherapy Report

At the 2024 World Congress of Brachytherapy (National Harbor, Washington DC, USA, July 10-13, 2024), breast cancer brachytherapy was extensively discussed during the Judith Stitt plenary session and two other sessions.

On Thursday, 11 July, the first breast session was dedicated to the “indications, techniques and results” of breast brachytherapy. During this session, which was moderated by Cristina Gutiérrez Miguélez, MD, PhD, (Institut Català d'Oncologia, Spain) and Jean-Michel Hannoun-Levi, MD, PhD, (Antoine Lacassagne Cancer Centre, France), Marta Gimeno-Morales, MD, PhD (Cancer Center Clínica Universidad de Navarra, Spain) reported the techniques that are used to apply and the clinical results thus achieved with very accelerated partial breast irradiation (vAPBI). This is a hot topic in the area of hypofractionated adjuvant radiation therapy.

The results of work by the GEC-ESTRO breast cancer working group (BCWG) were presented. They showed that the use of multi-catheter interstitial brachytherapy (MIB) enabled the completion of adjuvant breast irradiation in three, two or even one day with excellent long-term toxicity profiles and encouraging oncological outcomes for low-risk breast cancer (Brachytherapy, 2021;20(2):332-338; Radiother Oncol. 2024;194:110217). These results are in line with those found in the prospective phase 2 vAPBI TRIUMPH-T trial (Pract Radiat Oncol. 2023;13(4):314-320). Through the use of MIB-based vAPBI, it is possible to offer the patient a single fraction in a single treatment session (Brachytherapy, 2023;22(4):491-495).

Bridget Quinn, MD, PhD, (Virginia Commonwealth University Health Medical Center, USA) reported important data and perspectives regarding the management of ipsilateral breast cancer recurrence after initial breast-conserving treatment (BCT). One of the main points that Dr Quinn highlighted was that salvage mastectomy was no longer the only salvage option, according to the results provided by the Radiation Oncology Therapy Group 1014 phase-2 prospective trial (JAMA Oncol. 2020 Jan 1;6(1):75-82). These results showed that a second partial external beam irradiation of the breast achieved excellent local control and safety profile. Data provided by the GEC-ESTRO BCWG were also presented; these showed that MIB-based second BCT was not inferior to salvage mastectomy in terms of oncological outcome in a large propensity-score-matched cohort analysis (Int J Radiat Oncol Biol Phys. 2021;110(2):452-461). Selection criteria for discussion of a second BCT were reported according to a score that was recently proposed by the BCWG, which takes into account the time between the first and second surgeries, the patient’s suitability for vABPI and the molecular classification of the tumour (Int J Radiat Oncol Biol Phys. 2023;117(5):1200-1210).

 

After these first two talks, which were dedicated to new indications for the use of breast brachytherapy, the next speakers moved on to technical issues. Johann Tang, MD, (Novena Group, Singapore) detailed the different steps that are required in the use of MIB to treat the breast, while Bethany Anderson, MD, (University Wisconsin-Madison, USA) and Cathryn M. Yashar, MD, FABS, (University of California, San Diego, USA) detailed the single entry device procedures.

The second breast session was dedicated to the results of intra-operative radiation therapy (IORT) in an adjuvant breast irradiation setting. This session was moderated by Drs Bethany Anderson and Einsley Janowski, (University of Virginia, USA). During the first part of this session, Evelyn Martinez, MD, (Institut Català d'Oncologia, Spain) presented an extensive review of the literature regarding technical approaches (50kV and electron beam) and oncological outcomes that had been reported in the TARGIT-A (Lancet, 2014;383(9917):603-13) and ELIOT (Lancet Oncol. 2021;22(5):597-608) phase-3 randomised trials. The second part was a fantastic debate for (William Small, MD, Stritch School of Medicine, Loyola University, Chicago, USA) or against (Vratislav Strnad, MD, PhD, University Hospital Erlangen, Germany) the use of 50kV IORT in daily clinical practice. Dr Small reported interesting biological data that supported the concept of 50kV IORT. He reported the results of TARGIT-A subgroup analysis, which could be interpreted as non-inferior results in terms of local control compared with whole breast irradiation (WBI). Dr. Strnad presented a smart clinical and statistical analysis of the TARGIT-A trial results that led to the consideration of the use of 50kV IORT in breast cancer as being statistically inferior to WBI in terms of local control. His demonstration was in line with the updated consensus statement from the American Brachytherapy Society (Brachytherapy, 2022;21(6):726-747), which considers that IORT should not be the chosen protocol.

On Friday, 12 July, during the Judith Stitt plenary session (which comprised a presentation of the top five abstracts), Dr. Strnad presented the long-term, late side-effects that had been found in the GEC-ESTRO APBI phase-3 prospective randomised trial which had been submitted by Csaba Polgar, MD, PhD, (National Institute of Oncology, Hungary). Dr Anderson was the discussant of this abstract. Dr. Strnad demonstrated that MIB-based APBI provided significantly better results in terms of skin telangiectasia (p = 0.02) and brachial lymphedema (p = 0.03) with a median follow-up of 7.5 years (Lancet Oncol. 2023;24(3):262-272). The superiority of MIB-based APBI over WBI was also highly significant regarding late cosmesis assessment, reported either by the patient (p = 0.001) or by the physician (p = 0.049), also with a median follow-up of 7.5 years.

The 2024 World Brachytherapy Congress helped to promote breast brachytherapy as an essential irradiation technique that offers excellent oncological outcomes and late toxicity profiles for candidates that meet the criteria for its use. Due to the research programme that has been developed by the GEC-ESTRO BCWG, MIB-based APBI is being applied in new and promising directions such as vAPBI and second BCT for breast-cancer recurrence.

Prof Jean-Michel Hannoun-Levi

Radiation Therapy Department

Centre Antoine Lacassagne / University Cote d’Azur

Nice, France

Member of the ESTRO breast focus group

Prof Cristina Gutiérrez

Head of Brachytherapy Unit

Institut Català d'Oncologia

Barcelona, Spain

Member of the ESTRO breast focus group

 

Vratislav Strnad, GEC-ESTRO committee past-chair, presents the TARGIT-A trial results

 

Representatives of the GEC-ESTRO committee. From left to right: Peter Hoskin, Luca Tagliaferri, Jean-Michel Hannoun-Levi (chair-elect), Vratislav Strnad, Alina Sturdza, Peter Niehoff, Piotr Wojcieszek, Alexandra Stewart and Frank-André Siebert (chair).