ESTRO 2024 - Abstract Book

S406

Brachytherapy - Urology

ESTRO 2024

1123

Proffered Paper

Early results of LDR brachytherapy 108 Gy and ultrahypofractionated 5*5 Gy SBRT for prostate cancer

Jörg S. Zimmermann 1,2 , Florian Würschmidt 3 , Sebastian Munzert 4 , Carl Christian Eckert 4 , Nils Henrik Nicolay 5 , Christos Moustakis 1,5,6

1 Praxiszentrum Alstertal, Brachytherapie, Hamburg, Germany.

2 Katholisches Marienkrankenhaus, Urologie,

Hamburg, Germany. 4 Radiologische Allianz, Medizinphysik, Hamburg, Germany. 5 Universitätsklinikum Leipzig, Klinik und Poliklinik für Strahlentherapie, Leipzig, Germany. 6 Universitätsklinikum Münster, Klinik und Poliklinik für Strahlentherapie, Münster, Germany 3 Radiologische Allianz, Strahlentherapie, Hamburg, Germany.

Purpose/Objective:

Combination of normofractionated external beam radiotherapy and low dose-rate (LDR) brachytherapy is recognized as a very effective treatment for prostate cancer. Combining LDR brachytherapy with prostate SBRT shortens treatment times and may also combine radiobiological advantages of both modalities. Here we report early results of a short treatment course of LDR brachytherapy and 5-fraction SBRT regarding early oncological outcomes and treatment-related toxicities.

Material/Methods:

Between July 2021 and October 2023, 174 patients were treated with stranded iodine-125 LDR brachytherapy to 108 Gy and prostate SBRT with 5 x 5 Gy (100%Isodose), of whom 91 patients (52,3%) were treated with SBRT and consecutive LDR brachytherapy 4 weeks later and 83 patients (47,7%) with LDR brachytherapy 108 Gy followed by SBRT after a 3-month interval. Mean iPSA was 11,94 ng/ml, Gleason scores were mixed, 3+3, 3+4, 4+3, 4+4 with and without tertiary Gleason 5 pattern. In total, 4 patients exhibited low-risk, 109 patients had intermediate risk and 61 patients had high-risk disease (d´Amico). 37 patients received concomitant ADT for a maximum of 6 months. Mean patient age was 72.7 years (range 55-87 years). SBRT was admininistered in 5 fractions of 5 Gy every 2nd day. Daily cone beam CT imaging and if necessary adaptive planning was used. The target volume enclosed the prostate with a 3 mm margin, the seminal vesicles and also the first lymphatic channels around the seminal vesicles. Deep pelvic lymph nodes were not included. Functional parameters were assessed at 6 months using the EPIC-26 questionnaire as used by ICHOM (International Consortium for Health Outcomes Measurement, www.ichom.org) , and acute toxicities were recorded using CTCAE. Additionally, we assessed biochemical control and local control defined as a PSA increase > Nadir + 2ng/mL or use of any salvage treatment or ADT. More patient related details are shown in Fig. 1.

All patients provided informed written consent.