ESTRO 2025 - Abstract Book

S68

Invited Speaker

ESTRO 2025

the prostate [3]. Permanent implant have also the potential drawback of seed migration that can impact the dose indices [4]. Both methods provide biologically equivalent doses and when comapring the dose-volume histograms and dosimetric indices between LDR and HDR brachytherapy the needed D90 and V100 are mostly well achieved. Rectum and urethral doses are often higher when using seeds [5]. However, Wang et al found a better dose coverage dose conformity, and homogeneity using HDR [6] whereas Nickers et al. [7] showed slight superority of LDR prostate implants. In a more recent publication Solanki et al. demontrated similar dosimetry between LDR and HDR. They saw also that prostate high dose volumes, expressed in V150 and V200, were reduced when using HDR [8]. Murray et al. modelled that the risk for secondary cancers (bladder and rectum) are very low for both LDR and HDR [1] Henry et al. GEC-ESTRO ACROP prostate brachytherapy guidelines. Radiother Oncol. 2022 Feb;167:244-251. doi: 10.1016/j.radonc.2021.12.047. [2] Vigneault et al. The association of intraprostatic calcifications and dosimetry parameters with biochemical control after permanent prostate implant. Brachytherapy 18.6 (2019): 787-792. [3] Chibani et al. MCPI©: A sub-minute Monte Carlo dose calculation enginefor prostate implants. Med Phys 32 (2005) 3688-3698. [4] Pinkawa et al. Evaluation of source displacement and dose–volume changes after permanent prostate brachytherapy with stranded seeds. Radiother Oncol 84 (2007) 190-196. [5] Fröhlich et al. Comparative dosimetrical analysis of intensity-modulated arc therapy, CyberKnife therapy and image-guided interstitial HDR and LDR brachytherapy of low risk prostate cancer. Rep Pract Oncol Radiother. 2021 Apr 14;26(2):196-202. doi: 10.5603/RPOR.a2021.0028. PMID: 34211769; PMCID: PMC8241303. [6] Wang et al. Comparative study of dosimetry between high-dose-rate and permanent prostate implant brachytherapies in patients with prostate adenocarcinoma. Brachytherapy 5 (2006) 251-255. [7] Nickers et al. 192Ir or 125I prostate brachytherapy as a boost to external beam radiotherapy in locally advanced prostatic cancer: A dosimetric point of view. Radiother Oncol 78 (2006) 47-52. [8] Solanki et al. Transitioning From a Low-Dose-Rate to a High-Dose-Rate Prostate Brachytherapy Program: Comparing Initial Dosimetry and Improving Workflow Efficiency Through Targeted Interventions. Advances in Radiation Oncology (2019) 4, 103-111. [9] Murray et al. Modelling second malignancy risks from low dose rate and high dose rate brachytherapy as monotherapy for localised prostate cancer. Radiother Oncol 129 (2016) 293-9. brachytherapy and underline the long-term safety of using prostate brachytherapy [9]. To summarise, with a good implant, the dosimetric advantages of either LDR or HDR are small.

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Speaker Abstracts Future directions for brachytherapy boost: Clear skies or cloudy? Mario Terlizzi radiation oncology and brachytherapy, gustave roussy institute, villejuif, France

Abstract:

Brachytherapy (BT) boost is one of the standard treatments for dose escalation in prostate cancer, delivering excellent oncological outcomes. However, its use is in gradual decline worldwide, raising concerns about its long term sustainability. Despite its well-established efficacy, BT boost is offered to a shrinking proportion of eligible patients, with significant variations between countries due to differences in guidelines, infrastructure, and training availability. In France, as in many other regions, its decline is driven by logistical barriers, a diminishing number of trained specialists, patient