ESTRO 2025 - Abstract Book

S2023

Clinical - Urology

ESTRO 2025

2927

Digital Poster Treatment outcomes of prostate cancer patients aged 55 years or younger treated with definitive radiotherapy: TROD 09-005 study Caglayan Selenge Beduk Esen 1 , Aysenur Elmali 2 , Birhan Demirhan 3 , Ozan Cem Guler 4 , Selvi Tabak Dincer 5 , Ilknur Alsan Cetin 6 , Meral Kurt 7 , Mustafa Akin 8 , Ertugrul Senturk 9 , Serap Akyurek 10 , Halil Cumhur Yildirim 11 , Gulhan Guler Avci 12 , Pelin Altinok 13 , Hamit Basaran 14 , Gokhan Ozyigit 1 , Pervin Hurmuz 1 , Cem Onal 2,3,4 1 Department of Radiation Oncology, Hacettepe University Faculty of Medicine, Ankara, Turkey. 2 Department of Radiation Oncology, Baskent University Faculty of Medicine, Ankara, Turkey. 3 Department of Radiation Oncology, Iskenderun Gelisim Hospital, Hatay, Turkey. 4 Department of Radiation Oncology, Baskent University Faculty of Medicine Adana Dr. Turgut Noyan Research and Treatment Center, Adana, Turkey. 5 Department of Radiation Oncology, Prof. Dr. Cemil Tascioglu City Hospital, Istanbul, Turkey. 6 Department of Radiation Oncology, Marmara University Faculty of Medicine, Istanbul, Turkey. 7 Department of Radiation Oncology, Uludag University Faculty of Medicine, Bursa, Turkey. 8 Department of Radiation Oncology, Balıkesir Atatürk City Hospital, Balıkesir, Turkey. 9 Department of Radiation Oncology, Gazi University Faculty of Medicine, Ankara, Turkey. 10 Department of Radiation Oncology, Ankara University Faculty of Medicine, Ankara, Turkey. 11 Department of Radiation Oncology, Istanbul University Cerrahpasa Faculty of Medicine, Istanbul, Turkey. 12 Department of Radiation Oncology, Tokat Gaziosmanpasa University Faculty of Medicine, Tokat, Turkey. 13 Department of Radiation Oncology, Umraniye Research and Training Hospital, Istanbul, Turkey. 14 Department of Radiation Oncology, Selcuk University Faculty of Medicine, Konya, Turkey Purpose/Objective: Prostate cancer (PCa) is most commonly diagnosed in older men and is rare in those under the age of 55. Radical prostatectomy is often preferred over definitive radiotherapy (RT) in this group, largely due to the belief that younger patients face a higher risk of biochemical recurrence following RT [1, 2]. This multicenter study aimed to evaluate the oncologic outcomes and toxicity of RT in patients aged 55 years or younger. Material/Methods: The medical records of 180 PCa patients aged 55 years or younger, who were treated with definitive RT ± androgen deprivation therapy (ADT) across 12 cancer centers, were retrospectively reviewed. The primary endpoints included freedom from biochemical failure (FFBF) and prostate cancer-specific survival (PCSS). Secondary endpoints included overall survival (OS), acute and late genitourinary (GU) and gastrointestinal (GI) toxicities, local recurrence (LR), and distant metastasis (DM). Results: The median age was 54 years (range, 45 – 55), and the median PSA at diagnosis was 10.4 ng/mL (range, 1.9 – 382.4 ng/mL). Risk group distribution included 29% low-risk, 29% intermediate-risk, and 42% high-risk disease. The median RT dose was 76 Gy (range, 70 – 86 Gy), delivered in 38 fractions (range, 30 – 40). Three-dimensional conformal RT was used in 24%, and intensity-modulated RT in 76% of patients. Forty-six (26%) received pelvic RT. After a median follow-up of 106.2 months (IQR, 94.5 – 117.9), local recurrence (9%), distant metastasis (7%), LR + DM (5%), and isolated PSA progression (3%) were observed. The 8-year FFBF, PCSS, and OS were 85.7%, 93.8%, and 90.3%, respectively (Figure 1). The 8-year LR and DM rates were 11.2% and 9.1%, respectively. Univariate analysis identified PSA, clinical T stage, Gleason score, and risk group as significant for FFBF and PCSS. Multivariate analysis showed that advanced clinical stage (>T3a) and high Gleason score (>7) were independent predictors of worse FFBF and PCSS. For OS, only clinical T stage, Gleason score, and risk group were significant in univariate analysis but not in multivariate analysis. Acute and late grade ≥2 genitourinary toxicity occurred in 12% and 6%, respectively, and acute and late grade ≥2 gastrointestinal toxicity in 11% and 3%.