ESTRO 2024 - Abstract Book

S2410

Clinical - Urology

ESTRO 2024

surgical margins was performed to identify factors independently associated with ADT-free survival and progression-free survival (defined as local progression and/or distant metastasis diagnosed on PSMA PET/CT) among patients.

Results:

A total of 124 patients were included, of which 34% had pelvic nodal, 7% distant nodal, 50% bone, 2% pelvic nodal and bone, 6% distant nodal and bone and 1% distant nodal and visceral metastasis, respectively. As prior radical treatment, 87% underwent radical prostatectomy, 9% external beam radiation therapy and 4% brachytherapy. Median follow-up after treatment with SBRT was 2.1 years (IQR 1.5 – 3.8 yr). Median progression-free and ADT-free survival were 1.6 years (IQR 0.8 – 2.8 yr) and 1.6 years (IQR 0.9 – 2.6 years), respectively. One, two and three year ADT free survival were 80% (95%CI 72% – 87%), 57% (95%CI 46% – 68%), and 41% (95%CI 29%-53%), respectively. One, two and three year progression-free survival were 73% (95%CI 64% – 81%), 40% (95%CI 30% – 51%), and 22% (95%CI 13% – 31%), respectively. Of the 73 patients with clinical progression, 26% underwent repeated SBRT. Among patients previously treated with radical prostatectomy, pre-SBRT PSA (HR 1.11 95%CI 1.04 –1.17) and ≥pT3a (HR 4.08 95%CI 1.43 – 11.6) were independently and significantly associated with of ADT-free survival, whereas pre-SBRT PSA (HR 1.06 95%CI 1.01 – 1.12), positive surgical margins (HR 1.98 95%CI 1.13 –3.47) and stage ≥pT3a (HR 2.48 95%CI 1.25– 4.92) were significantly associated with progression-free survival.

Conclusion:

SBRT is a suitable treatment option for oligorecurrent prostate cancer staged with PSMA PET/CT, allowing to defer the initiation of ADT in over half of the patients at two years. Pre- SBRT PSA, stage ≥pT3a and positive surgical margins are found to be independently associated with treatment response which can assist patient selection.

Keywords: PSMA PET/CT, SBRT, oligometastatic prostate cancer

1221

Proffered Paper

Using routinely collected data for long term toxicity assessment; a case-study from the CHHiP trial

Lara Philipps 1 , Clare Griffin 1 , Clare Cruickshank 1 , Vicki Hinder 1 , Shama Hassan 1 , Julia Pugh 1 , Lucy Kilburn 1 , Isabel Syndikus 2 , Emma Hall 1 , on behalf of CHHiP TMG 1 1 The Institute of Cancer Research, Clinical Trials & Statistics Unit, London, United Kingdom. 2 Clatterbridge Cancer Centre, Department of Oncology, Wirral, United Kingdom

Purpose/Objective: