ESTRO 2025 - Abstract Book

S1967

Clinical - Urology

ESTRO 2025

Material/Methods: 56 patients with prostate cancer treated on MR-Linac with UHF-RT between 2021 and 2024 were evaluated within the MRL-01 study (NCT04172753). Two different regimens have been used: RT in five fractions (total dose of 36.25, 37.5 or 40 Gy) or RT in seven fractions (total dose 42.7 Gy); using 7 MV step-and-shoot IMRT. Acute and late toxicity were scored according to RTOG and CTCAE V4.0, as well as with patient questionnaires. Acute toxicity was defined as maximal score at 3 months and late toxicity 12 months after the end of RT. Evaluated toxicity included: IPS-score, ICIQ score and NCI-PRO-CTCAE (CTC for GU urinary frequency, urgency, hematuria and urgency; CTC for GI diarrhea, rectal bleeding, proctitis, incontinence and ulcer; RTOG for GU and GI toxicity).

Results: Median follow-up was 16.3 months (range 3-38 months). Mostly patients with intermediate risk prostate cancer have been included (91.1%; table 1). No deaths or biochemical recurrences were observed. No significant difference regarding acute toxicity between the two different regimens was found. Grade 3 acute toxicity regarding IPS-score (defined as score of 20-35) was reported in two patients 3 months after RT- end. This tends to normalize, and no ≥G3 IPS- score was observed at 12 months. No further ≥G3 genitourinary (GU) or gastrointestinal (GI) acute or late toxicity was observed in our cohort during follow-up (Fig. 1).