ESTRO 2024 - Abstract Book

S2409

Clinical - Urology

ESTRO 2024

Conclusion:

In SBRT treatment for localized prostate cancer, the adoption of a high biologically effective dose did not significantly improve tumor control rates and survival rates. Clinicians should weigh treatment effectiveness and potential adverse effects when devising personalized treatment plans to maximize therapeutic benefits for patients.

Keywords: Stereotactic Body Radiation Therapy, Dose

1214

Digital Poster

Predictors of successful response to SBRT in PSMA PET/CT staged oligorecurrent prostate cancer

Timo FW Soeterik 1 , Marcin Miszczyk 2 , Justyna Kociolek 3 , Carlo Greco 3 , Giulio Francolini 4 , Pietro Garlatti 4 , Mateusz Bilski 5 , Eline H Huele 6 , Helena M Verkooijen 6 , Jochem RN van der Voort van Zyp 1 , Wietse Eppinga 1 , Joanne M van der Velden 1 1 University Medical Center Utrecht, Department of Radiation Oncology, Utrecht, Netherlands. 2 Maria Skłodowska Curie National Research Institute of Oncology, 3rd Department of Radiotherapy and Chemotherapy, Gliwice, Poland. 3 The Champalimaud Centre for the Unknown, Department of Radiation Oncology, Lisbon, Portugal. 4 Azienda Ospedaliero-Universitaria Careggi, Department of Radiation Oncology, Florence, Italy. 5 Medical University of Lublin, Department of Radiotherapy, Lublin, Poland. 6 University Medical Center Utrecht, Division of Imaging and Oncology, Utrecht, Netherlands

Purpose/Objective:

The widespread adoption of PSMA PET/CT to assist prostate cancer (PCa) staging has led to earlier and more frequent detection of oligometastatic PCa. However, data regarding the outcomes of patients staged with PSMA PET/CT undergoing metastasis directed therapy with SBRT is scarce, and patient selection in daily practice remains a challenge. Therefore, we aim assess the outcomes SBRT in oligometastatic metachronous PCa staged with PSMA PET/CT and to identify factors independently associated with androgen deprivation therapy (ADT)-free and progression-free survival.

Material/Methods:

In this retrospective multicenter study, we included patients with metachronous oligometastatic PCa (defined as ≤5 pelvic or distant nodal, osseous or visceral lesions), treated with SBRT to all metastatic sites aiming to postpone ADT, at five European tertiary referral centers. All patients were staged with PSMA PET/CT. Varying fractionation schemes were used, including 18, 20 or 24 Gy in 1 fraction, 9, 10 or 12 Gy in 3 fractions or 6, 7 or 9 Gy in 5 fractions. Multivariable cox regression analysis including pre- SBRT PSA, histopathological outcomes (pT2 vs ≥pT3a), and