ESTRO 2024 - Abstract Book

S2363

Clinical - Urology

ESTRO 2024

protocol or dose criteria were violated and approved by the attending oncologist. Pts were followed and PSA levels were monitored at the end of Hypo-MRgSRT, 1-month, 3-month, and every 6 months later. Toxicities were assessed using the Common Terminology Criteria for Adverse Events (CTCAE) v5.0. Biochemical progression-free survival (bPFS) was estimated using the Kaplan-Meier (KM) method. The Expanded Prostate Cancer Index Composite (EPIC) questionnaire was used to assess patient-reported outcomes (PROs).

Results:

Out of 60 patients, 31 who completed Hypo-MRgSRT were finally included. Patient characteristics are shown in Table.1. All 31 patients received ADT treatment. All fractions (N=31x20=620) were successfully delivered with the median duration of 43 minutes (range: 36-53minutes). Adapt-to-position (ATP) and adapt-to-shape (ATS) were conducted in 568(92%) and 52 (8%) fractions. The median follow-up duration was 8.3months(mo) (1.3mo-30.3mo). PSA levels dropped below 0.05ng/ml within 1-month in all but two patients (0.17ng/ml and 0.47ng/ml). Only one patient with oligo-recurrence diagnosed at pre-SRT PSMA-PET experienced PSA progression at month-11 after MRgSRT, and then subsequent PSMA-PET showed another oligo-progression.. The estimated bPFS was 87.5% (95%CI: 67.3%-100%) at 12-month. All pts remained alive (100% OS). Only 2 acute (<3months) G2 diarrhea and 1 late G2 PR bleeding were scored in 3 pts. No ≥G3 events were reported. PROs were insignificantly different between baseline, 3-month, 6-month, and 12-month (Kruskal-Wallis test p>0.05).