S1312
Clinical - Urology
ESTRO 2026
Probanza Manchon 1 , Claudia Garcia Gonzalo 1 , Emma Sanz 1 , Jesús Romero Fernández 1 1 Radiation Oncology, Hospital Universitario Puerta de Hierro Majadahonda, Majadahonda, Spain. 2 Odontology, Universidad CEU San Pablo, Madrid, Spain Purpose/Objective: To evaluate long-term outcomes and patterns of late biochemical recurrences following salvage radiotherapy (SRT) in patients with biochemical recurrence after radical prostatectomy, with extended follow-up beyond conventional surveillance periods. Material/Methods: Retrospective analysis of a prospectively maintained database including 53 consecutive patients with PSA elevation after radical prostatectomy treated with SRT between May 2009-October 2014. Patients received either 66 Gy/33 fractions or 70 Gy/35 fractions with IMRT. Mean age was 72 years. Median follow-up was 9.45 years (range 0.21-12.75 years), with data collection extending 11 years after the last patient completed treatment. Baseline characteristics and toxicity were compared between dose groups using chi-square test. Biochemical progression-free survival was estimated using Kaplan-Meier method and compared with log-rank test. Statistical analyses were performed using IBM SPSS Statistics version 29. Adverse events were assessed using CTCAE v5.0. Results: Baseline characteristics are shown in Table 1. The 70 Gy group had significantly higher rates of perineural invasion (65% vs 24%, p=0.002) and higher proportion of Gleason 8-10 tumors (12.9% vs 4.5%), both adverse prognostic factors. Despite this, biochemical progression-free survival (bPFS) at 5 and 10 years was comparable: 68% and 40-45% for 66 Gy versus 60% and 35-40% for 70 Gy (p=NS), suggesting potential compensation by dose escalation. These findings align with the SAKK 09/10 randomized trial (64 Gy vs 70 Gy), which showed no benefit from dose intensification. Notably, late recurrences continued beyond 5 years, with sustained bPFS decline between years 5-10. Chronic toxicity was acceptable with one grade 3 genitourinary event in the 66 Gy group (incontinence surgery at 2 years in a previously incontinent patient) and no grade ≥ 3 events in the 70 Gy group (Table 2).
Figure 1. Independent predictors of acute toxicity after prostate radiotherapy. Rectal V60 Gy was the only significant variable (OR 1.07; 95% CI 1.01–1.14; p=0.017). Rectal V50 Gy, bladder V65 Gy, and age were not significant Conclusion: Rectal V60 Gy remains a clinically relevant predictor of acute toxicity after prostate RT. When translated by EQD2, the risk threshold aligns with V ≈ 53 Gy (20 fx) and V ≈ 32 Gy (5 fx), providing a biologically grounded benchmark for moderate and ultrahypofractionation. These findings support maintaining intermediate-dose rectal sparing as a quality indicator and advance the equitable implementation of ESTRO Vision 2030 standards in resource-limited centres. References: 1. Michalski JM et al. Radiation dose–volume effects in radiation-induced rectal injury. Int J Radiat Oncol Biol Phys.2010;76(3 Suppl):S123-S129.2. Lievens Y, Ricardi U, Poortmans P et al. Optimal Health for All, Together: ESTRO Vision 2030. Radiother Oncol.2019;136:86-97. doi: 10.1016/j.radonc.2019.03.031.3. U.S. DHHS, NIH, NCI. Common Terminology Criteria for Adverse Events (CTCAE) v5.0. Nov 27 2017.4. Dearnaley D et al. Conventional vs hypofractionated IMRT for prostate cancer: 5-year outcomes of CHHiP. Lancet Oncol.2016;17(8):1047-1060. doi: 10.1016/S1470- 2045(16)30102-4.5. Brand DH et al. IMRT vs SBRT for prostate cancer (PACE-B): acute toxicity results. Lancet Oncol. 2019;20(11):1531-1543. doi: 10.1016/S1470- 2045(19)30569-8. Keywords: Prostate cancer, Acute toxicity, EQD2 Long-term outcomes and patterns of late recurrence after salvage radiotherapy post- prostatectomy: 11-year follow-up analysis Clara Caballero Valls 1 , Joaquín Velasco Jiménez 1,2 , Marta López Valcárcel 1 , Irma Zapata Paz 1 , Beatriz Gil Haro 1 , Peppa Abelairas Ramos 1 , Susana Sánchez Rico 1 , Arancha Gallego Barranco 1 , María Ángeles Ruíz Rodríguez 1 , Irene Ávila Gómez 1 , José Cantillana Barrenas 1 , María Hernández Miguel 1 , Raquel Benlloch Rodriguez 1 , Sofía Santana Jiménez 1 , Cristina de la Fuente Alonso 1 , Sofía Córdoba Largo 1 , María Isabel García Berrocal 1 , Sofía Merino Pedraza 1 , Gonzalo Digital Poster 4935
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