ESTRO 2025 - Abstract Book

S1284

Clinical – Lower GI

ESTRO 2025

From January to June 2024, 100 patients with localized or locally advanced prostate cancer were prospectively followed at the radiotherapy department at the National Institute of Oncology. All patients received radical RT, with or without ADT. QoL outcomes were assessed at baseline, 6, 12, and 24 months using the University of California Los Angeles-Prostate Cancer Index (UCLA-PCI). Demographics, comorbidities, tumor characteristics, and treatment details were recorded. Longitudinal trajectories of BF and BB were analyzed using growth mixture models. Results: PROMs data were available for 98 patients. Of these, 75% underwent image-guided RT (IGRT), while 25% received non-IGRT techniques. All patients were treated with VMAT. Treatment volumes were prostate-only (30%), prostate + seminal vesicles (50%), and prostate + seminal vesicles + pelvic nodes (20%). ADT was administered before or during RT in 20% and after RT in 40% while RT alone was used in 40% of patients. Baseline mean scores were 92.1 ± 14.8 for BF and 91.5 ± 19.7 for BB. A minimal proportion of patients reported persistent bowel worsening at 24 months. Three BF trajectories were identified, with ≥3 comorbidities and 3D-CRT linked to worse outcomes (OR=3.20, 95% CI 1.60–6.90; OR=2.00, 95% CI 1.10–3.60). For BB, two trajectories emerged: diabetes and non-IGRT were associated with poorer outcomes (OR=1.80, 95% CI 1.05–2.95; OR=2.40, 95% CI 1.50–3.85). Conclusion: In this cohort, IGRT and the absence of comorbidities were associated with better BF and BB trajectories over a 2 year follow-up period. These findings underscore the importance of considering individual patient factors, such as comorbidities and RT technique, during multidisciplinary discussions to optimize prostate cancer treatment outcomes and tailor therapies to patient needs.

Keywords: bowel function, prostate cancer, quality of life