S1318
Clinical - Urology
ESTRO 2026
discrimination (AUC 0.78). No significant interaction between age and rectal DVH parameters was detected.
Purpose/Objective: Polypharmacy is increasingly common among men receiving prostate radiotherapy, yet its impact on treatment tolerance is unclear. Polypharmacy and medication inappropriateness are highly prevalent in older oncology patients and have been linked to adverse treatment outcomes in other settings [1]. Older patients often take multiple medications that may influence inflammation, repair capacity, or organ sensitivity. This study assessed whether the number or appropriateness of medications—quantified through the Medication Inappropriateness Assessment (MIA)— affects the incidence of acute gastrointestinal or genitourinary (GI/GU) toxicity after curative-intent prostate radiotherapy [2]. Material/Methods: We retrospectively reviewed 164 consecutive men treated with external-beam radiotherapy (76–78 Gy in 2 Gy fractions). For each patient, the total medication count and MIA score were recorded at treatment initiation; polypharmacy was defined as ≥ 5 concurrent drugs. The endpoint was any acute GI/GU toxicity (CTCAE v5.0) occurring during or within 3 months post- RT [3]. Associations between medication-related variables and toxicity were analysed using t-tests, χ² tests, and multivariable logistic regression adjusting for age and baseline comorbidity. Results: Median medication count was 6 (IQR 4–9); 61 % of patients met the polypharmacy threshold. Acute toxicity occurred in 25 (15.2 %) patients. No significant relationship was found between total medication number, polypharmacy status, or MIA score and acute toxicity (all p > 0.20). After adjustment for age and comorbidity, no medication-related variable predicted toxicity. Model discrimination was low (AUC = 0.58), indicating minimal explanatory contribution from medication metrics. Conclusion: Polypharmacy and medication appropriateness did not predict acute toxicity following prostate radiotherapy. These findings suggest that, despite the high prevalence of polypharmacy in this population, medication profiles have limited influence on short- term radiation tolerance. Clinical focus should therefore prioritise optimising treatment planning and supportive care rather than medication count reduction. Clarifying non-contributory risk factors such as polypharmacy is essential for efficient, evidence- based toxicity prevention and aligns with ESTRO Vision 2030 goals of value-driven, patient-centred
Figure 1. Age-related acute toxicity after prostate radiotherapy. (A) Incidence of toxicity by age group. (B) Model performance curve for combined predictors (age + rectal V60 Gy, AUC = 0.78). Conclusion: In routine prostate RT, chronological age confers a modest but independent increase in early GI/GU toxicity, even after accounting for rectal dose exposure. A simple risk signal—age plus V60 Gy— offers an immediately applicable framework for triaging supportive care and follow-up intensity. Embedding both patient- and dose-related factors into everyday decision-making supports personalised and equitable implementation of hypofractionated prostate RT in resource-constrained settings.Age should complement—not replace—dosimetric criteria in toxicity prediction. Combining both parameters can optimise resource allocation and patient counselling, supporting the goals of ESTRO Vision 2030 for personalised and equitable radiotherapy. References: 1. Wortel RC, Incrocci L, Pos FJ, Lebesque JV, Witte MG, van der Heide UA, van Herk M, Heemsbergen WD. Acute toxicity after image-guided intensity modulated radiation therapy compared to 3D conformal radiation therapy in prostate cancer patients. Int J Radiat Oncol Biol Phys. 2015 Mar 15;91(4):737-44. doi: 10.1016/j.ijrobp.2014.12.017. PMID: 25752386.2. Michalski, Jeff M. et al. Radiation Dose– Volume Effects in Radiation-Induced Rectal Injury International Journal of Radiation Oncology, Biology, Physics, Volume 76, Issue 3, S123 - S129 Keywords: Prostate cancer, age, acute toxicity Digital Poster 5141 Polypharmacy and medication appropriateness do not predict acute toxicity after prostate radiotherapy: a single-centre real-world study Milos Grujic 1,2 , Marija Zivkovic Radojevic 1,2 , Neda Milosavljevic 1,2 1 Department of Clinical Oncology, Faculty of Medical Sciences, Kragujevac, Serbia. 2 Center for Radiation Oncology, University Clinical Center Kragujevac, Kragujevac, Serbia
radiotherapy. References:
1. Puts MTE, Tu HA, Tourangeau A, et al. Factors influencing adherence to cancer treatment in older adults: a systematic review. Ann Oncol. 2014;25(3):564-
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