From once-weekly to semi-weekly whole prostate gland stereotactic radiotherapy with focal boosting: Primary endpoint analysis of the multicenter phase II hypo-FLAME 2.0 trial

• Published in: Radiotherapy and oncology 2023-08, Vol.185, p.109713-109713, Article 109713
• Main Authors: De Cock, Lisa, Draulans, Cédric, Pos, Floris J., Isebaert, Sofie, De Roover, Robin, van der Heide, Uulke A., Smeenk, Robert J., Kunze-Busch, Martina, van der Voort van Zyp, Jochem, de Boer, Hans, Kerkmeijer, Linda G.W., Haustermans, Karin
• Format: Article
• Language: English
• Subjects: Focal boost; Gastrointestinal Diseases - etiology; Humans; Male; Overall treatment time; Prostate; Prostate cancer; Prostatic Neoplasms - radiotherapy; Prostatic Neoplasms - surgery; Quality of Life; Radiation Injuries - etiology; Radiosurgery - adverse effects; Radiosurgery - methods; Stereotactic body Radiotherapy; Ultra-hypofractionation; Urogenital System
• ISSN: 0167-8140; 1879-0887
• DOI: 10.1016/j.radonc.2023.109713

•The overall treatment time of focal boosted prostate SBRT can safely be reduced.•No acute grade ≥3 toxicity was reported for the semi-weekly (hypo-FLAME 2.0) schedule.•Less grade 2 GU toxicity was found for the once- compared to the semi-weekly schedule.•Patients should be counselled about short-term benefits of a protracted schedule. The hypo-FLAME trial showed that once-weekly (QW) focal boosted prostate stereotactic body radiotherapy (SBRT) is associated with acceptable acute genitourinary (GU) and gastrointestinal (GI) toxicity. Currently, we investigated the safety of reducing the overall treatment time (OTT) of focal boosted prostate SBRT from 29 to 15 days. Patients with intermediate- and high-risk prostate cancer were treated with SBRT delivering 35 Gy in 5 fractions to the whole prostate gland with an iso-toxic boost up to 50 Gy to the intraprostatic lesion(s) in a semi-weekly (BIW) schedule. The primary endpoint was radiation-induced acute toxicity (CTCAE v5.0). Changes in quality of life (QoL) were examined in terms of proportions achieving a minimal clinically important change (MCIC). Finally, acute toxicity and QoL scores of the BIW schedule were compared with the results of the prior QW hypo-FLAME schedule (n = 100). Between August 2020 and February 2022, 124 patients were enrolled and treated BIW. No grade ≥3 GU or GI toxicity was observed. The 90-days cumulative incidence of grade 2 GU and GI toxicity rates were 47.5% and 7.4%, respectively. Patients treated QW scored significant less grade 2 GU toxicity (34.0%, p = 0.01). No significant differences in acute GI toxicity were observed. Furthermore, patients treated QW had a superior acute bowel and urinary QoL. Semi-weekly prostate SBRT with iso-toxic focal boosting is associated with acceptable acute GU and GI toxicity. Based on the comparison between the QW and BIW schedule, patients should be counselled regarding the short-term advantages of a more protracted schedule. Registration number ClinicalTrials.gov: NCT04045717.