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P005: PSMA-PET- and mpMRI-guided focal radiation dose escalation in primary prostate cancer patients – a planned safety analysis of a two-armed prospective phase II trial (HypoFocal)

Spohn S.K.B.1, Gainey M.2, Kamps M.3, Gratzke C.3, Ruf J.4, Benndorf M.5, Zschaeck S.6, Ghadjar P.6, Baltas D.2, Grosu A.L.1, Zambolgou C.1
1University Medical Center Freiburg, Dept. of Radiation Oncology, Freiburg, Germany, 2University Medical Center Freiburg, Division of Medical Physics - Departmant of Radiation Oncology, Freiburg, Germany, 3University Medical Center Freiburg, Dept. of Urology, Freiburg, Germany, 4University Medical Center Freiburg , Dept. of Nuclear Medicine, Freiburg, Germany, 5University Medical Center Freiburg , Dept. of Radiology, Freiburg, Germany, 6Charité – Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Dept. of Radiation Oncology, Berlin, Germany
13th European Multidisciplinary Congress on Urological Cancers
Date – Time - Location
25 November 2021, 00:00 - 00:00, PDF
EMUC e-posters - e-posters
Prostate Cancer, Localised - Basic Research & Trials

Introduction & Objectives

Radiotherapy (RT) with focal dose escalation to multiparametric magnet resonance tomography- (mpMRI) and positron emission tomography targeting prostate specific membrane antigen- (PSMA-PET) defined boost volumes might improve oncology outcomes of primary prostate cancer (PCa) patients due to superior intraprostatic tumour mass (ITM) coverage. The HypoFocal phase II trial investigates the safety of PSMA-PET-implementation in focal therapy planning in 2 non-randomized arms. Here we present on the planned safety analysis after 6 months of follow-up (FU).

Materials & Methods

Key inclusion criteria were intermediate- and high-risk PCa patients with cN0 and cM0 in mpMRI and PSMA-PET. Key exclusion criteria was any prior treatment to the pelvis. Arm A was treated with 60 Gy in 20 fractions to the prostate with integrated boost (SIB) up to 75 Gy to mpMRI- and PSMA-PET-defined ITMs. Arm B was treated with single fraction high-dose-rate brachytherapy (HDR-BT) with 15 Gy to the prostate and SIB of up to 19 Gy to the ITMs, followed by RT with 44 Gy in 20 fractions. 32% of patients in arm A and 40% in arm B received androgen deprivation therapy. Gastrointestinal (GI) and genitourinary (GU) toxicities were assessed according to CTCAE v5.0. IPSS score was measured and quality of life (QoL) assessed with the EORTC questionnaires QLQ-PR25 and QLQ-PR30.


25 patients were enrolled in each study arm in two centers (Freiburg and Berlin). Median ITM in MRI was significantly smaller than in PET (1.4 vs 2.8 ml). Median boost volumes were 10.2 ml in arm A and 6.8 ml in arm B, respectively. Median mean dose to the boost volume was 70 Gy (range 64–75 Gy) in arm A and median D90 to the boost volume was 19 Gy (range 15–21 Gy) in arm B.  Cumulative grade 0, 1 and 2 GU toxicities were 0%, 64% and 36% in arm A and 0%, 52% and 48% in arm B, respectively. Cumulative grade 0, 1 and 2 GI toxicities were 12%, 72% and 16% in arm A and 24%, 64% and 12% in arm B, respectively. No grade 3 GU and GI toxicities were observed at 6 months FU. Two patients in arm A experienced grade 3 GI toxicities 9 and 12 months after RT, related to biopsy. Toxicities, IPSS and QoL-scores were not statistically significantly different between baselines and 6 months of FU in both arms.


Combined PSMA-PET and mpMRI-based ITM definition results in significantly larger boost volumes. Despite large boost volumes, focal dose escalation was feasible for both arms, showing acceptable acute GU and GI toxicities without compromising QoL. Radiation proctitis demands careful management.

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