ESTRO 2024 - Abstract Book

S125

Invited Speaker

ESTRO 2024

National Research Institute of Oncology, Gliwce Branch, Brachytherapy, Gliwice, Poland

Abstract:

Local recurrence of prostate cancer after definitive external beam radiotherapy (EBRT) has many options for management, from observation to salvage radical prostatectomy. Surprisingly, irradiation may also be used to treat the relapse after primary EBRT. The most common techniques used are brachytherapy and stereotactic body radiotherapy. It is efficient and probably due to schedules using ablative doses per fraction (>7Gy). This lecture aims to report the toxicity of the brachytherapy in this setting. Such knowledge helps to choose the optimal method in real life clinical situations and raises physicians' awareness of potential complications.

3542

Toxicity of SBRT

Christina Schröder

Cantonal Hospital Winterthur, Radiation Oncology Department, Winterthur, Switzerland. Peter MacCallum Cancer Centre, Radiation Oncology, Melbourne, Australia

Abstract:

Radiotherapy is one of the main pillars of prostate cancer treatment for localized disease. However, up to a third of patients develop a recurrence after primary radiotherapy. With modern imaging like PSMA-PET/CT, the distinction between a local recurrence and a regional recurrence or even metastatic disease is possible with a high sensitivity and specificity. For patients with an isolated local recurrence, there are different treatment options like salvage surgery but also non-surgical options like re-irradiation, both brachytherapy and external beam radiotherapy (EBRT). In terms of EBRT, stereotactic radiotherapy (SBRT) has proven to be feasible with a promising oncological outcome and acceptable toxicity rates not only after EBRT but also brachytherapy. While traditionally a lot of re-irradiation case series have been done with a Cyberknife, there has been increasing evidence for re-irradiation using a C-arm LINAC or a MR-Linac in the last years. There is no conclusive data regarding the benefit of any treatment machine to date. Generally there is a wide range of reported toxicity when using SBRT in the re-irradiation setting for radio-recurrent prostate cancer. Although the overall ≥ grade (G) 2 late GU and GI toxicity has been reported to be around 20% and 5% on average, percentages of up to 51.8% and 25% have been reported in selected studies. There were two large meta-analysis from 2020 and 2021 by Ingrosso et al and Munoz et al. Additionally, we performed a complementary Meta-analysis of studies published 2021 to 2023 specifically including patients that received SBRT in the re-irradiation setting. Ingrosso et al. compared different non-surgical approaches and found lowest rates for incontinence (3%) and obstruction (4%) brachytherapy and EBRT as well as low rates for strictures (2%). Munoz focussed on EBRT and brachytherapy in the re-irradiation setting and overall found G≥3 late toxicity of 8.7% (95%CI: 5.8–13%). For cohorts were patients received EBRT as first RT and SBRT in the re-irradiation setting the rate of acute and late >G3 toxicity was 2.3% each (1-5%). In our meta-analysis, the pooled rate of acute GU and GI toxicity ≥G2 was 13% (95% CI: 7% - 18%) and 2% (95% CI: 0% - 4%). For late GU and GI toxicity, those values were 25% (95% CI: 14% - 35%) and was 5% (95% CI: 1% - 9%).