This retrospective cohort study aimed to explore the association between short-term genitourinary (GU) and gastrointestinal (GI) toxicity and oncological outcomes in high-risk prostate cancer patients treated with external beam radiotherapy (EBRT) alone or with high-dose-rate brachytherapy (HDR-BT). Patient/material and methods: High-risk prostate cancer patients treated at Örebro University Hospital (2008-2021) were divided into two cohorts based on treatment modality: EBRT-only (66 Gy/22 fractions), EBRT-BT (42 Gy/14 fractions + 14.5 Gy HDR-BT-boost). Maximum 6-month toxicity grade was categorised as: GU-low (grade 0-1), GU-high (grade ≥ 2), GI-low (grade 0) and GI-high (grade ≥ 1), respectively. Freedom from biochemical failure (FFBF), metastasis-free survival (MFS) and overall survival were compared between the low- and high- toxicity groups, using Kaplan-Meier and Cox proportional hazards regression. Prostate cancer-specific mortality was compared between the groups using the Aalen-Johansen method and Fine-Gray regression.
The EBRT-only cohort encompassed 114 and 162 patients for GU- and GI-analyses. The EBRT-BT cohort comprised 306 patients for GU- and 344 patients for GI-analyses. High GU-toxicity was associated with inferior FFBF (adjusted hazard ratio (aHR) = 2.57, 95% Confidence Interval [CI] = 1.32-5.00) and MFS (aHR = 2.22, 95% CI = 1.21-4.07) in the EBRT-only but not in the EBRT-BT cohort. No statistically significant associations were found between GI-toxicity and oncological outcomes.
Early grade ≥ 2 GU-toxicity was linked to worse FFBR and MFS after EBRT alone, whereas no such association was seen after EBRT-BT. GI toxicity showed no prognostic impact. These exploratory findings warrant validation in larger studies addressing interactions between patient-, tumour- and treatment-related factors.
Acta oncologica (Stockholm, Sweden). 2026 Mar 23*** epublish ***
Jenny Kahlmeter Brandell, Antonis Valachis, Henrik Ugge, Daniel Smith, Bengt Johansson
a. Department of Oncology, Faculty of Medicine and Health, Örebro University Hospital, Örebro University, Örebro, Sweden, ., Department of Oncology, Faculty of Medicine and Health, Örebro University Hospital, Örebro University, Örebro, Sweden., Department of Urology, Faculty of Medicine and Health, Örebro University, Örebro, Sweden; School of Medical Sciences, Örebro University, Örebro, Sweden., Clinical Epidemiology and Biostatistics, School of Medical Sciences, Örebro University, Örebro, Sweden.