Marieke van Son

169 RE-SALVAGE FOCAL HDR-BT Both imaging modalities were repeated six months later at a PSA-value of 4.6 ng/ml (PSADT nine months). The same recurrence location was revealed on the 68Ga-PSMA PET-CT and confirmed by the mp-MRI (Figure 5) and MRI-guided target biopsies (<1% adenocarcinoma in one out of four cores, suggested Gleason score 3+3=6). Figure 5 – Diagnostic 3T mp-MRI revealing second recurrence lesion Transversal plane of the diagnostic 3T mp-MRI revealing a suspect lesion in the left dorsal peripheral zone. Delineations of the urethra (yellow), rectum (green), prostate (red), gross tumor volume (GTV, blue), and clinical target volume (CTV, orange) are shown. (a) T2-weighted image, (b) ADC image, (c) K-trans image Re-salvage treatment Eleven years after the initial prostate cancer treatment and two years after receiving the first MRI-guided focal salvage HDR-BT, the patient was re-treated. A total of eight catheters were placed in and around the recurrence lesion (Figure 6). D95 for the CTV was 19.1Gy, D1cc of rectum and bladder was 11Gy, and D10 of the urethra was 15.1Gy. No perioperative complications occurred. The postoperative PSA values at one, three, and six months were 0.37 ng/ml, <0.10 ng/ml, and <0.10 ng/ml, respectively. The patient experienced transient flatulence complaints without further need for any therapeutic interventions. Three months after treatment, tamsulosin 0.4 mg was again prescribed. No grade ≥3 toxicity occurred. The mp-MRI six months post-treatment revealed a re- duction in both diffusion restriction and contrast enhancement at the treated location. An overview of the course of PSA values over time is presented in Figure 7. 9