S1173
Clinical - Urology
ESTRO 2026
Digital Poster Highlight 1151
Deaths due to second malignancies in localised prostate cancer: long term prospective data from two phase III trials Abdenour Nabid 1 , Nathalie Carrier 2 , André-Guy Martin 3 , Eric Vigneault 3 , Jean-Paul Bahary 4 , Thu Van Nguyen 4 , Peter Vavassis 5 , Marc-André Brassard 6 , Boris Bahoric 7 , Robert Archambault 8 , François Vincent 9 , Redouane Bettahar 10 , Marie Duclos 11 , Derek Wilke 12 , Luis Souhami 11 1 Radiooncologie, CIUSSS de l'Estrie - CHUS, Sherbrooke, Canada. 2 Statistique, CIUSSS de l'Estrie - CHUS, Sherbrooke, Canada. 3 Radiooncologie, CHU de Québec - Université Laval, Québec, Canada. 4 Radiooncologie, Centre Hospitalier de l'Université de Montréal, Montréal, Canada. 5 Radiooncologie, Hôpital Maisonneuve-Rosemont, Montréal, Canada. 6 Radiooncologie, Centre intégré universitaire de santé et de services sociaux du Saguenay-Lac-Saint-Jean, Chicoutimi, Canada. 7 Radiation Oncology, Jewish General Hospital, Montréal, Canada. 8 Radiooncologie, Centre intégré de santé et de services sociaux de l'Outaouais, Rimouski, Canada. 9 Radiooncologie, Centre hospitalier régional de Trois-Rivières, Trois- Rivières, Canada. 10 Radiooncologie, Centre de santé et de services sociaux de Rimouski-Neigette, Montréal, Canada. 11 Radiation Oncology, McGill University Health Centre, Montréal, Canada. 12 Radiation Oncology, Nova Scotia Cancer Centrel, Halifax, Canada Purpose/Objective: The purpose of this analysis was to establish the frequency and characteristics of a second malignancy (SM) as cause of death in a cohort of localised prostate patients (pts) treated with radiotherapy (RT) with or without androgen deprivation therapy (ADT). Material/Methods: From October 2000 to September 2010, 1230 pts were randomized into 2 Phase 3 trial. 630 with high risk prostate cancer (HRPCa) treated with long-term ADT and RT and 600 with intermediate risk prostate cancer (IRPCa) treated with RT with or without short-term ADT. Causes of death related to SM were established from data sent by the different investigators and centrally reviewed. They were based on clinical records, family members’ information, death certificates, and family physician records. All data were compiled untilOctober 2025. Results: With a median follow up of 17.4 years (IQR 13.2-20.6), 65.5% of pts (806/1230) had died, Of these, 73% HRPCa (460/630) and 57.7% IRPCa (346/600), p<0.001. 23.8% of pts (293/1230) developed a SM without significant difference between HRPCa and IRPCa (24.6% vs 23.0%, p=0.51). Of the 293 pts developing a SM, 255 had died and 201 (78.8%) died as
Conclusion: This large real-world study with long-term follow- up, demonstrated the prognostic value of PSA bounce and PSA kinetics for cancer-specific outcomes, in PCa patients treated with definitive radiotherapy and PSA increase (absolute value >1 ng/dL).Findings align withpreviousstudies describing Phoenix Criteria limitations inreal-world clinical practice. References: 1.van Altena EJ, Jansen BH, Korbee ML, et al. Prostate- specific Membrane Antigen Positron Emission Tomography Before Reaching the Phoenix Criteria for Biochemical Recurrence of Prostate Cancer After Radiotherapy: Earlier Detection of Recurrences. EurUrol Oncol.2025;8(2):417- 424. doi:10.1016/j.euo.2024.09.0152.Subiela JD, Gomis E, Maldonado A, et al. Clinical Usefulness of Prostate-specific Membrane Antigen-ligand Positron Emission Tomography/Computed Tomography for the Detection of Prostate Cancer Biochemical Recurrence after Primary Radiation Therapy in Patients with Prostate-specific Antigen Below the Phoenix Threshold: Systematic Review and Meta-analysis. Clin Oncol R Coll Radiol G B.2023;35(12):676- 688. doi:10.1016/j.clon.2023.09.012 Keywords: PSA Kinetics, PSA bounce, Prostate Cancer
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