Acute toxicity and patient-reported quality of life during daily online adaptive radiotherapy versus conventional IGRT for localized prostate cancer: a prospective parallel cohort study

Abstract Purpose This study aimed to prospectively compare clinician-reported acute toxicity and patient-reported health-related quality of life (HRQoL) between daily cone-beam CT (CBCT)-based online adaptive radiotherapy (oART) and image-guided radiotherapy (IGRT) in patients with localized prostate cancer treated with moderate hypofractionation. Materials and methods In this prospective study, 74 patients with localized prostate cancer received either CBCT-based oART ( n = 43) or CBCT-based IGRT ( n = 31) with 62/57.6/48 Gy in 20 fractions, allocated pragmatically by convenience. Acute gastrointestinal (GI) and genitourinary (GU) toxicity was assessed weekly using CTCAE v5.0, and HRQoL was evaluated using the EORTC QLQ-C30 questionnaire at baseline and the end of therapy. Between-group differences were tested using Boschloo’s exact test, Wilcoxon rank-sum test and t -tests; temporal and between-group changes were evaluated based on minimally clinically important differences (MCIDs). Results Baseline patient and treatment characteristics were similar, except for more high-/very high-risk tumors in the oART group (40.5% vs. 9.7%; p = 0.03). Online ART was associated with more favorable gastrointestinal toxicity, reflected by lower maximum toxicity grades ( p = 0.028). Maximum genitourinary toxicity was comparable between groups ( p = 0.793). More IGRT patients exceeded MCID thresholds for fatigue (74% vs. 37%; p = 0.004), physical functioning (27% vs. 3%; p = 0.009), and role functioning (48.1% vs. 22.9%; p = 0.04). Differences for global health, pain, social function, and diarrhea were not statistically significant but consistently favored oART. Conclusion Daily CBCT-based oART and IGRT were both well tolerated, with low rates of high-grade acute toxicity. In this exploratory analysis, oART was associated with a more favorable GI toxicity profile and better preservation of HRQoL. These hypothesis-generating findings suggest that adaptive workflows may provide measurable patient-centered benefits during prostate radiotherapy and warrant confirmation in larger prospective studies.