S1188
Clinical - Urology
ESTRO 2026
ov/41164810/ Keywords: Prostate cancer; adaptive radiotherapy; toxicity.
recorded in the database). Categorical comparisons used χ² /Fisher tests and continuous variables used t- test/Wilcoxon as appropriate; p < 0.05 considered significant. Results: Cohort characteristics: total N=93 (Group 2 n=39, Group 3 n=48). Mean age was 71.3 ± 5.4 years in Group 2 vs 74.7 ± 7.5 in Group 3 (p = 0.020). PSA at diagnosis medians were 9.4 (IQR 5.2) vs 13.3 (IQR 8.7).Acute GU toxicity (<G3) occurred in 56.4% of Group 2 vs 77.1% of Group 3 (trend towards lower acute GU toxicity with oART+BT; p = 0.064).Acute GI toxicity (<G3) occurred in 28.2% of Group 2 vs 54.2% of Group 3 (p = 0.018), showing a statistically significant reduction with oART+BT.Chronic GU toxicity (<G3) was 10.3% (Group 2) vs 2.1% (Group 3) (p = 0.169). Chronic GI toxicity was rare in both groups ( ≈ 2–3%, p = 1.00).
Proffered Paper 1689 Late Toxicity and Longitudinal Quality-of-Life after Pelvis-inclusive SBRT vs IMRT for High-Risk Prostate Cancer: The SRAM Randomized Phase II Trial Darren MC Poon 1,2 , Kenneth Wong 1 , Daisy Lam 1 , David Johnson 1 , Landon Chan 1 , CM Chu 3 , Anthony CF Ng 4 , Frankie Mo 1 , Anthony TC Chan 1 , Tony Mok 1 1 Department of Clinical Oncology, The Chinese University of Hong Kong, Hong Kong, Hong Kong. 2 Comprehensive Oncology Center, Hong Kong Sanatorium & Hospital, Hong Kong, Hong Kong. 3 Department of Imaging & Interventional Radiology, The Chinese University of Hong Kong, Hong Kong, Hong Kong. 4 Department of Surgery, The Chinese University of Hong Kong, Hong Kong, Hong Kong Purpose/Objective: The SRAM randomized phase II trial (NCT03938649) evaluated the comparative late toxicity and longitudinal quality-of-life (QoL) outcomes of stereotactic body radiotherapy (SBRT) versus conventional intensity-modulated radiotherapy (IMRT) delivered to the prostate and pelvis in men with high- risk prostate cancer (HR-PC). The primary endpoint of the trial, acute toxicity, previously indicated significantly lower gastrointestinal (GI) toxicities with SBRT. This report focuses on late toxicity (6–12 months post-treatment) and QoL data. Material/Methods: Eligible men with node-negative HR-PC (T3–T4 and/or PSA > 20 ng/mL and/or Gleason score ≥ 8) were randomised 1:1 to either SBRT (n=60; 40 Gy/25 Gy to prostate/pelvis in 5 weekly fractions) or IMRT (n=61; 50 Gy/25 fractions to pelvis, then 26 Gy/13 fractions to prostate over 7–8 weeks). All received 18–24 months of androgen deprivation therapy. RapidArc™ volumetric-modulated arc therapy with daily fiducial- based cone-beam CT was used, and no rectal spacers were employed. Late toxicities were prospectively graded by CTCAE v4.0. QoL was measured using the Expanded Prostate Cancer Index Composite (EPIC) and International Prostate Symptom Score (IPSS) at 6, 9, and 12 months. Toxicity and QOL scores comparisons between groups used chi-square and t-tests, respectively.
Conclusion: In our institutional series, oART combined with a brachytherapy boost was associated with a significant reduction in acute GI toxicity and a non-significant trend toward lower acute GU toxicity compared with oART alone, Group 3 showed a tendency toward greater acute gut toxicity and a significant difference in acute gut toxicity, importantly, these results do not imply causality, only an association. Chronic toxicity rates were low and did not differ significantly. Differences in baseline characteristics (older age and higher PSA in the oART-only group) may confound results. Prospective evaluation with longer follow-up is warranted to confirm these findings and to assess clinical outcomes (biochemical control and late toxicity). References: https://pubmed.ncbi.nlm.nih.gov/39499306/https://pu bmed.ncbi.nlm.nih.gov/40516969/https://pubmed.ncb i.nlm.nih.gov/39705230/https://pubmed.ncbi.nlm.nih.g
Results: The incidence of late grade ≥ 2 GI toxicity was 16.7%
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