ESTRO 2025 - Abstract Book

S1955

Clinical - Urology

ESTRO 2025

University Hospital, Geneva, Switzerland. 23 Radiation Oncology, 1. Ghent University Hospital and department of Human structure and repair, Ghent University, Ghent, Belgium. 24 Applied Mathematics, 26. Computer Science and Statistics, Ghent University, Ghent, Belgium. 25 1. Department of Human structure and repair, Ghent University, Ghent, Belgium Purpose/Objective: For prostate cancer patients with PET-detected nodal pelvic oligorecurrence after a primary treatment, the first results of the randomized phase II PEACE-V STORM trial has shown that, compared to metastasis directed therapy (MDT), elective nodal pelvic radiotherapy (ENRT) is a more effective treatment option to achieve pelvic disease control. Here we analyze the subsequent management of loco-regional relapses and report the quality of life (QoL) outcomes of MDT vs ENRT in patients randomized in the PEACE-V STORM trial. Material/Methods: Patients diagnosed with ≤5 PET -detected pelvic nodal oligorecurrence following local treatment for prostate cancer were randomized 1:1 in a phase II superiority trial (NCT03569241) between MDT and 6 months of androgen deprivation therapy (ADT), or ENRT (25x1.8Gy) with MDT and 6 months of ADT. In case of radiotherapy, SBRT (3x10Gy) was used for MDT, with a simultaneous integrated boost for ENRT. QoL was assessed by EORTC QLQ-C-30 and QLQ-PR-25 questionnaires over a 2-year period as a part of a statistically defined QoL analysis. Results: Among the 190 evaluable patients (MDT: 93 and ENRT: 97) of the 196 patients randomized (MDT, n=99 and ENRT, n=97), 35 patients in total across both treatment arms presented a locoregional relapse. At 3-years, 19 patients treated with MDT (20%) presented with a pelvic relapse vs 2 treated with ENRT (2%). Of these, prostate bed recurrences were observed in 9 patients (9%) treated in MDT vs 5 (5%) in ENRT. The subsequent therapy was MDT (+/- ADT) in 10 (29%, all in the MDT arm), systemic therapy only in 7 (20%), and observation at last follow-up in 18 (51%). Differences in management between arms is depicted in Table 1. QLQ-C30 scores showed no significant differences between MDT and ENRT, except for a worse physical functioning at month 24 for ENRT (mean decline - 7.7 vs -1.3) (Fig. 1). No significant differences on QLQ-PR25 scores were observed, except slightly better bowel symptoms at 18-months for ENRT. Decline in sexual activity and increase in ADT-related symptoms during the first 6 months was similar in both arms, returning to baseline at month-12. Conclusion: At 3-years, patients treated with MDT experienced a higher rate of second locoregional relapses and were more frequently managed with additional MDT ± ADT compared to those treated with ENRT. In analogy to physician reported toxicity, QoL measures confirmed the optimal tolerance and equivalence of ENRT compared to MDT.