ESTRO 2024 - Abstract Book

S2413

Clinical - Urology

ESTRO 2024

Iosif Strouthos 1,2 , Efstratios Karagiannis 1,2 , Anna Antoniou 1 , Constantina Cloconi 1 , Georgios Antorkas 1 , Yiannis Roussakis 1 , Alexis Vrachimis 1 , Constantinos Zamboglou 1,3 , Konstantinos Ferentinos 1,2 1 German Oncology Center, Department of Radiation Oncology, Limassol, Cyprus. 2 European University Cyprus, University Hospital, Nicosia, Cyprus. 3 University of Freiburg, Medical Center, Faculty of Medicine, Freiburg, Germany

Purpose/Objective:

To report acute toxicity and impact on early quality of life (QoL) of a patient cohort staged with 18F-PSMA-PET/CT, treated with a combination of prostate high dose-rate HDR brachytherapy (HDR-BT) and prostate/seminal vesicle EBRT for intermediate and high-risk prostate cancer in a phase II prospective trial (NCT05003752).

Material/Methods:

In this prospective phase II trial, a total of 41 patients with intermediate (IR) and high risk (HR) prostate cancer, were recruited to receive a combination of hypofractionated external beam radiotherapy (EBRT) to the prostate/seminal vesicles of 36 Gy (12 fractions of 3 Gy each) delivered in consecutive days, followed by single fraction real time HDR BT of 14 Gy. Patients also received short-term (3-6 months) or long-term (>6 months) androgen deprivation therapy (ADT). All patients were both conventionally staged with prostate multi-parametric MRI (mpMRI), abdomen/pelvis CT and bone scintigraphy, with additional PSMA-PET/CT prior to their study inclusion. Acute genito-urinary (GU) and gastro-intestinal (GI) toxicity was assessed according to Radiation Therapy Oncology Group (RTOG) and European Organisation for Research and Treatment of Cancer (EORTC) questionnaires. Patient QoL was evaluated through Expanded Prostate Cancer Index Composite for Clinical Practice (EPIC-CP) questionnaires. Erectile function was assessed by International Index for Erectile Function -5 (IIEF-5) questionnaire. Fourty-one patients (NCCN 48.8% UIR, 43.9% HR and 7.3% VHR) completed treatment and reached at least 9 months of follow-up (FU) at the time of the current analysis. Median FU was 16 months (IQ range 9-24). Median age was 72 years, median PSA before treatment was 11.0 ng/mL (5.0-28.3) and median volume of the prostate was 36.5 cc (14.9-68.2). Short-term ADT was administered to 43.9% of patients whereas 48.8% received long-term ADT, the rest of the patients did not receive hormonal therapy. No severe (i.e. Grade 2-4) acute events were recorded. The most common acute GU symptoms were nocturia and dysuria (29% and 20% respectively), whereas the most common acute GI events were increased bowel movements and pain during defecation (10% and 5% respectively). A significant decline from baseline compared to 3 months post treatment was observed both in hormonal and sexual domains, with high severity exhibited as a worsening from 12% to 38% and from 0% to 5%, respectively. No other domains exhibited any significant decline (urinary, and bowel ). Results:

Conclusion:

The evaluation of the primary results of the presented prospective phase II trial suggests that this hypofractionated combined radiotherapeutic scheme is a well-tolerated, presenting no early, severe adverse events. Moreover,