PPP04 Presentation Time: 10:57 AM

Purpose

To report acute and early late 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 brachytherapy (HDR-BT) and prostate/seminal vesicle external beam radiation therapy (EBRT) for intermediate and high-risk prostate cancer in a phase II prospective trial (NCT05003752).

Materials and Methods

In this prospective phase II trial, a total of 41 patients with intermediate (IR), high (HR) and very high risk (VHR) prostate cancer, were recruited to receive a combination of hypofractionated 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, as well as early late 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.

Results

Fourty-one patients (NCCN 48.8% UIR, 43.9% HR and 7.3% VHR) completed treatment and reached at least 14 months of follow-up (FU) at the time of the current analysis. Median FU was 20 months (IQ range 14-28). 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).

Conclusions

The evaluation of the primary results of the presented prospective phase II trial suggests that the proposed hypofractionated combined radiotherapeutic scheme is a well-tolerated, presenting no acute or early late severe adverse events. Moreover, patient reported outcomes confirm these results, since no significant decline in any domain from baseline values was recorded.