S1160
Clinical - Urology
ESTRO 2026
with intermediate-risk, ISUP 2 prostate cancer accrued, with a 12-month follow-up. Screening prostate GTV was confirmed as unifocal on biopsy and MRI/PSMA PET. The simulation comprised CT, mpMRI, and PSMA PET. Treatment consisted of MRL-guided focal SABR to DIL/GTV, with 26Gy in two fractions, one week apart, with adaptation and motion management. Outcome metrics included fraction duration, toxicity (CTCAE v5) and quality of life (QOL) (EPIC-26/QLQ-C30). Tumour measures comprised post-treatment 3-monthly PSA/testosterone, 6-month and 12-month mpMRI, and 12-month PSMA PET. Results:
Conclusion: 18F-DCFPyL-PET/CT demonstrates high-sensitivity for detecting recurrent-PC at low PSA-levels, significantly impacting therapeutic-decisions and optimizing clinical-management. These findings support its integration into guidelines for managing early BCR of PC. References: https://doi.org/10.3390/cancers17081272 Keywords: Prostate cancer, biochemical recurrence, 18F-PSMA Digital Poster Highlight 934 MRL guided adapted focal SABR for unifocal intermediate risk prostate cancer: interim analysis Kianan Lim Joon 1 , Greg Jack 2 , Mark Tacey 3 , Leah McDermott 3 , Eddie Lau 4,5 , Farshad Foroudi 3,6 , Michael Chao 3,6 , Ee Siang Choong 3 , Sandie Fisher 3 , Drew Smith 3 , Kelvin Lim 5 , Sze Ting Lee 4 , Joseph Ischia 2 , Damien Bolton 2 , Trish Jenkins 3 , Vincent Khoo 7 , Daryl Lim Joon 3,6 1 Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, Australia. 2 Surgery, Austin Health, Melbourne, Australia. 3 Radiation Oncology, Olivia Newton-John Cancer Centre, Melbourne, Australia. 4 Molecular Imaging and Therapy, Austin Health, Melbourne, Australia. 5 Radiology, Austin Health, Melbourne, Australia. 6 Medical Imaging and Radiation Sciences, Monash University, Melbourne, Australia. 7 Clinical Oncology, Royal Marsden, London, United Kingdom Purpose/Objective: The interim analysis evaluates the effectiveness of the MR-guided linear accelerator (MRL) focal stereotactic ablative radiotherapy (SABR) for intermediate-risk prostate cancer, focusing on workflow, initial clinical outcomes, and imaging responses. Material/Methods: An R-IDEAL 2b analysis of a single-centre prospective Phase 1 study, examining the first 10 consecutive men
The cohort's mean age was 71.4 years (SD 5.23), with a mean PSA level of 6.96 ng/mL (2.72). Nine were T1c and one was T2c. The PIRAD score (P) was either P4 or P5, with a mean MRI GTV diameter of 16.44mm (3.24), and a mean prostate volume of 36.40 cc (7.02). Dosimetric objectives were achieved for the both reference and delivered plans. Average treatment times were 50 minutes (15.22). Reported toxicities included transient grade 1 side effects of diarrhea, dysuria and urinary frequency. 20% of patients developed episodes of grade 1 or 2 erectile dysfunction during the 12-months. Overall QOL scores EPIC-26 decreased from screening score of 71.52 (9.99) to 69.29 (14.69), and QLQ-C30 from 93.24 (8.12) to 88.11 (15.52) at 12 months. All showed a reduction in PSA from an average of 6.96 ng/mL (2.72) at baseline to 2.90 ng/mL (3.03) at 12 months, while testosterone levels remained stable. The 6-month MRI revealed that 80% of patients achieved a complete response (CR), with an improved PIRAD score to P2, and 20% had a partial response (PR), with the PIRAD score maintained at P4. At 12-months, MRI CR and PR were 86% and 14%, with one patient improving from PIRAD 4 to 2. The 12-month PSMA PET has shown a
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