Multimodal image and mapping guided focal salvage high-dose-rate brachytherapy for local recurrent prostate cancer.

Abstract

122 Background: Image guided brachytherapy and mapping biopsy could reduce the toxicity of the total salvage brachytherapy. This study evaluate the tumor control and the tolerance of a focal real time salvage high-dose-rate (HDR) brachytherapy to treat the local relapse as defined on transperineal mapping biopsy, multipara-metric MRI and Choline PETSCAN on the same treatment planning. Methods: Between October 2013 and June 2016, Twenty-nine patients with local relapse on Choline PET Scan after a primary irradiation had a salvage HDR Brachytherapy (2 fractions of 10 Gy within 4-6 hours in one implant) without hormone. One month before brachytherapy All patients had real time transperineal randomized European regions standardised magnetic resonance imaging (MRI) prostate biopsies and targeted biopsies with a fusion of T2 MRI sequence /CholinePETscan (50 % SUV) to intraoperative transrectal ultrasound one month before brachytherapy. We used Flex Focus 400 ultrasound machine BK, Vitesse 3.0 and 3 D navigation with EXII Stepper in order to use the result of mapping biopsy for real time HDR brachytherapy treatment planning study. Tumor control was measure with phoenix definition and Kaplan-Meier. The GU and GI toxicity were measure with CTCAE V 3. Results: 13 Low risk, 10 Intermediate risk, 8 High risk, initially treated with 3 Iodine brachytherapy ( 160 GY), 15 EBRT ≥ 78 Gy and 7 EBRT ≤ 70 gy were include. The number of biopsy (mean volume, 21 cm3; SD, 6.7). Prostate Volume (mean volume, 29.7 cm3; SD, 12.5). CTV Volume (mean volume, 13.3 cm3; SD, 6.7). Mean dose to 90% of the prostate was 11.4 Gy (SD, 1.45). Mean dose to 90% of the CTV was 21.1 Gy (SD, 1.45). Mean dose to 90% of the CTVmri was 27.6 Gy (SD, 3.4). The biologic disease free survival at 2 years is 65 % (Kaplan-Meier). Disease without hormone survival at 2 years is 86,5%. The chronic toxicity ( > 6 mois) was 6 Gu and 4 GI for grade ≤ 2 and 1 GU grade 3 (total incontinence). Conclusions: Focal, mapping and multimodal image guided salvage HDR brachytherapy for recurrent prostate cancer is a feasible therapy. This approach has to be evaluated in multicenter cohort.