ESTRO 2025 - Abstract Book

S1877

Clinical - Urology

ESTRO 2025

110

Digital Poster The impact of age on clinicopathological features and treatment outcomes in patients with localized prostate cancer undergoing definitive radiotherapy Cem Onal 1,2 , Ozan Cem Guler 1 , Aysenur Elmali 2 , Birhan Demirhan 3 , Melek Yavuz 1 1 Department of Radiation Oncology, Baskent University Faculty of Medicine, Adana, Turkey. 2 Department of Radiation Oncology, Baskent University Faculty of Medicine, Ankara, Turkey. 3 Division of Radiation Oncology, Iskenderun Gelisim Hospital, Hatay, Turkey Purpose/Objective: Background: This study assessed the biochemical disease-free survival (bDFS), prostate cancer-specific survival (PCSS) and overall survival (OS) in patients aged <70 and ≥70 years following definitive radiotherapy (RT). It also analyzed the correlation between age at diagnosis and clinicopathological characteristics of prostate cancer (PCa). Material/Methods: The prognostic factors for bDFS, PCSS, and OS were determined through univariable and multivariable analyses. Two age groups were also compared in terms of acute and late grade ≥ 2 genitourinary (GU) and gastrointestinal (GI) toxicities, the predictors of which were determined through logistic regression analysis. Results: Of the 1,328 patients, 715 (53.8%) and 613 (46.2%) were aged <70 and ≥70 years, respectively. Median follow -up time was 84.5 months. Patients aged ≥70 had significantly higher rates of comorbidities, including cardiac disease (27.9% vs. 21.5%; p<0.001) and diabetes (9.0% vs. 7.8%; p=0.02). This group also had a higher prevalence of high ISUP grades and high-risk disease compared to those aged <70. Additionally, a greater proportion of patients aged ≥70 had undergone transurethral resection of the prostate and received androgen deprivation therapy. Disease progression, occurring at a median of 35.6 months (1.1 – 159.6 months) after completion of RT, was observed in 177 patients (13.3%). No significant differences in the 7-year bDFS (86.3% vs. 86.8%; P=0.28) and PCSS rates (92.9% vs. 93.3%; p=0.83) were found between the ≥70 and <70 age groups (Figure 1). The 5 -year local recurrence (LR) rates were 2.3% for patients aged ≥70 and 1.6% for those aged <70, with no significant difference (p = 0.23) (Figure 2). Similarly, 5-year distant metastasis (DM) rates did not significantly differ between the age groups (10.1% vs. 8.7%; p = 0.52). However, the 5-year non- prostate cancer mortality rate was significantly higher in the ≥70 age group compared to the <70 age group (17.1% vs. 7.4%; p < 0.001). The multivariable analysis identified advanced clinical T stage, high ISUP grade, and high-risk disease as predictors of poor bDFS and PCSS. Metastatic lymph nodes also predicted worse bDFS. For OS, negative factors included age ≥70 years, cardiac events at diagnosis, advanced stage, higher ISUP grade, and non-use of the simultaneous integrated boost technique.