ESTRO 2024 Congress report

ESTRO 2024 of course allowed for the exchange of scientific and clinical observations and enabled the establishment of many great contacts that will allow for the further development of radiation oncology. It gathered more than 7000 participants and a record number of submitted abstracts.

Pre-Meeting Course

Adventure with brachytherapy started on May 3. Participants had an excellent opportunity to develop their knowledge and clarify puzzles during the pre-meeting course titled: “Radiobiology and modelling in brachytherapy”. It was a wonderful opportunity to listen to eminent lecturers: Artur Chyrek, Franziska Eckert, Dorin Todor, Bradley Pieters, Christian Kiristis, Kari Tanderup, Taran Paulsen Hellebust, Peter Hoskin, Jose Luis Guinot, Luca Tagliaferri, Alex Stewart, Cyrus Chargari, Frank-Andre Siebert and Piotr Wojcieszek. The first part of the course was general and it contained subjects involving biology, α/β, re-irradiation, pulse dose rate (PDR) vs. high dose rate (HDR), brachytherapy vs. the best external beam techniques and high dose regions (focal/integrated boost). It finished with a lecture by Dr Wojcieszek about the significance of fractionation in brachytherapy, with the main question being whether less is always better.

The second part of the course considered localisations, and the radiobiology of cervical, prostate, breast, skin, head-and-neck and gastrointestinal (GI) cancers was precisely described and explained.

Cyceron once said: "History - witness of time, light of truth, life of memory, teacher of life, herald of the future.” In line with this, the course finished with a lecture on the history of radiobiology in brachytherapy by Professor Chargari.

Brachytherapy sessions during ESTRO 2024

On May 4, during the first brachytherapy session, which was chaired by Professor Siebert, the background and practical hints regarding the commissioning of TG43 guidelines were discussed with model-based treatment planning systems in brachytherapy. This session was addressed mainly to medical physicists. Lecturers explained how the use of special test cases of model-based dose-calculation algorithms (MBDCAs) could help in the commissioning process. The audience may have learned about the benefits and limitations of MBDCAs in clinical practice.

The next session was in a symposium format, chaired by Hathal Haddad and Mateusz Bilski, titled “Above and beyond: toxicity after re-irradiation of the prostate”. Potential risks of prostate re-irradiation with stereotactic body radiotherapy (SBRT) and brachytherapy were presented. Aspects of focal re-irradiation were explained. The symposium was finished with the completion of a very interesting poll during which session chairs asked participants about their own everyday clinical practice that involved diagnostic and radiotherapy modality selection during prostate re-irradiation.  

During that day, proffered papers on breast and prostate cancer were presented in a session moderated by Vratislav Strnad and Dr Bilski.

Irene Martinez showed excellent results regarding local control (LC) rates after brachytherapy boost in locally advanced (T1-T4N+) breast cancer after neoadjuvant chemotherapy.

Hong Linh Ha reported the toxicity and value of brachytherapy boost in breast cancer patients who had high-risk factors such as young age, extensive intraductal components, positive surgical margins and triple-negative biological types. A safe, few-side-effects profile with excellent LC was presented.

Mohammed Abdul-Latif described favourable oncological outcomes and survival rates after accelerated partial breast re-irradiation in patients with second ipsilateral breast-tumor events who had been treated conservatively.

Jörg Zimmermann presented early results of low-dose-rate (LDR) brachytherapy with 108Gy and ultra-hypofractionated 5x5Gy SBRT. It was stated that this combination might be both an effective and cost-effective treatment.

Visus Ignacio investigated the impact of comorbidity in the association between biochemical failure and overall survival (OS) rates in a high-risk and very-high-risk prostate cancer series of patients who had been treated with HDR boost brachytherapy or exclusively with external beam radiation therapy (EBRT). The results showed that high- and very-high-risk patients with little comorbidity benefited from brachytherapy boost treatment.

Ioannis Androulakis’s study affirmed the stability of electromagnetic tracking (EMT) measurements in intraoperative prostate transrectal-ultrasound-based HDR brachytherapy. The introduction of EMT measurements in this setting revealed minor to severe needle reconstruction errors that remained undetected in clinical practice.

Later that day another symposium session, chaired by Alex Stewart and Georgina Fröhlich, considered the subject of HDR fractionation and how low can we go? The radiobiology of HDR fractionation, hypofractionation experiences in prostate cancer, and possible reductions in fractions used in cervical and breast cancers were presented.

The session of proffered papers in gynaecological brachytherapy, chaired by Alina Sturdza and Ewa Burchardt, consisted of six lectures.

Linda Rossi showed that a new system for automated adaptive treatment planning for image-guided cervical cancer brachytherapy, named “BiCycle”, reduced total daily planning time by approximately 35 minutes and led to dosimetric advantages.

Richa Tiwari showed initial experience indicating that pre-rectal installation of hydrogel during image-guided brachytherapy was feasible and safe and had the potential to improve the therapeutic index in the treatment of locally advanced cervical cancer, even in cases in which the anatomy is not conducive to the treatment.

Elizabeth Chuk showed that a less resource-intensive brachytherapy fractionation schedule of 24Gy/three fractions is a safe alternative to 28Gy/four fractions for the definitive treatment of cervical cancer.

Memory Bvochora-Nsingo spoke about how educational approaches have helped to bridge the gap in knowledge in Africa during the implementation of interstitial brachytherapy for cervical cancer.

Vincent Dick showed that image-guided adaptive brachytherapy (IGABT) alone can be used successfully in salvage settings in small superficial vaginal recurrences of endometrial cancer. More advanced tumours should be treated with a combination of EBRT and IGABT. 

Sabrina Reichl presented a systematic review of published papers that discussed brachytherapy for recurrent gynaecological tumours.

The next day started with a session moderated by Jose Luis Guinot. It involved a teaching lecture on the subject of the role of brachytherapy (interventional radiotherapy) in dose escalation for organ preservation in head-and-neck cancer. It was presented by Ashwini Budrukkar from India.

Later that day there was a symposium session for medical physicists, chaired by Asa Carlsson Tedgren and Grzegorz Bielęda, which involved advances in brachytherapy physics. Talks on in-vivo quality assurance, multi-criteria optimisation with artificial intelligence (AI) aspects for brachytherapy treatment planning, new directions for 3D printing in brachytherapy and the use of AI to optimise doses in brachytherapy were presented.

Next, proffered papers in GI, head, neck, skin and eye brachytherapy, chaired by Evert Van Limbergen and Michele De Brabandere, were presented.

Ngu Wah Than showed that in small rectal cancers (≤3cm), commencing treatment with contact X-ray brachytherapy as opposed to EBRT was associated with improved OS, despite an increased risk of grades 1 or 2 rectal bleeding. However, there was no significant improvement in terms of disease-free survival, local regrowth or organ preservation rates with this treatment strategy.

Elena Riggenbach presented results showing that (intra-operative radiotherapy with HDR brachytherapy as a way to escalate doses led to excellent LC in soft-tissue sarcomas of the extremities. Ida Kloosterman presented an experience of using 3D-printed moulds for paediatric brachytherapy. The GEC-ESTRO Best Junior Presentation by Lennart Pors showed that LC and eye preservation rates after treatment with ruthenium-106 brachytherapy were high. Visual acuity decline in the first five years after treatment was gradual and continuous, due to the late effects of radiation therapy. Nevertheless, visual outcomes were good, as even some eyes with centrally located tumours retained useful vision and 49% of all patients had no visual impairment after five years.

MY Musa showed a follow-up study of the use of a hybrid technique, HDR intra-luminal brachytherapy followed by image-modulated radiotherapy, for the definitive treatment of oral tongue small-cell cancer. Superior outcomes in terms of swallowing function compared with surgery were presented.

Automation and AI have significant potential to create more efficient workflows and to provide a more consistent quality of brachytherapy. A symposium on AI developments and automation for brachytherapy was chaired by Kari Tanderup and Bruno Fionda. The use of AI for automation contouring and planning as well as the possible use of ChatGPT in brachytherapy were presented topics.

The final session that day, chaired by Christian Kirisits and Grzegorz Bielęda, covered proffered papers in physics brachytherapy. The ESTRO-Elekta Brachytherapy Award was given to Teun van Wagenberg for a time-resolved analysis of clinical dose metrics for HDR brachytherapy error detection.

On the final day, a mini oral session for brachytherapy, chaired by Georgina Fröhlich and Magdalena Stankiewicz, took place. Eight papers that considered SBRT vs. SBRT + HDR-boost in prostate cancer, accelerated partial breast irradiation with multi-catheter HDR brachytherapy after 25 years of follow-up and salvage HDR for recurrent head-and-neck cancers were presented.

The last session was the poster discussion, chaired by Professor Pieters, for which 12 posters were selected. Dr Haddad presented the subject of integration of AI into interstitial HDR brachytherapy for liver tumours. Federico Mastroleo presented the results of the post-operative keloid irradiation (POKER) study, which supported the use of surgery and adjuvant brachytherapy to control keloid relapses.

Conclusions

All the sessions were amazing and showed that the use of brachytherapy/interventional radiotherapy is constantly growing and evolving. I would like to give many thanks to all the chairs, co-chairs and lecturers for this amazing adventure. You gave us another “HDR boost” to our everyday clinical and scientific work!

if you were registered for the congress and if you are interested in more precise information from all the sessions, recorded videos can be easily found with this link https://estro2024.estro.org/schedule.

Mateusz Bilski, MD, PhD

Deputy head of Department of Brachytherapy, Saint John’s Cancer Center, Lublin, Poland

Radiotherapy Department, Medical University of Lublin, Poland

Radiotherapy Department, Saint John’s Cancer Center, Lublin, Poland